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FAQs about Hang-On, Overflow Box, J-Tube, Siphon Selection

Related Articles: Overflow Box Arrangements, Plumbing Marine Systems by Bob Fenner, Myth of the One Inch Beast (Why Relying on One Inch Overflows... or Overflow! Is foolhardy) by Scott Vallembois, The Flowrates through various Bulkheads (In relation to overflow drains) by Scott Vallembois, Plumbing Return Manifolds, Refugiums,

Related FAQs: Overflows 1, Overflows 2, Overflows 3, Overflows 4, & FAQs on: Rationale/Use, Sizing, Through-Hull Fittings, Plumbing, Troubleshooting/Repair... Marine Plumbing 1, Marine Plumbing 2, Marine Plumbing 3, Marine Plumbing 4, Marine Plumbing 5, Marine Plumbing 6, Plumbing 7, Plumbing 8, Plumbing 9, Plumbing 10, Plumbing 11, Plumbing 12, Plumbing 13, Plumbing 14, Plumbing 15, Plumbing 16, Plumbing 17, Plumbing 18, Holes & Drilling, Durso Standpipes, Make Up Water Systems, Pumps, Plumbing, Circulation, Sumps, Refugiums, Marine Circulation 2, Gear Selection for Circulation, Pump Problems, Fish-Only Marine Set-ups, Fish-Only Marine Systems 2, FOWLR/Fish and Invertebrate Systems, Reef Systems, Coldwater Systems, Small Systems, Large Systems, Water Changes, Surge Devices,

They clog very often and need regular cleaning. The clogging can/will cause the tank to overflow and perhaps your return pump to run dry.

Frustration setting up overflow box     2/18/13
I just installed an Eshopps PF-1000 overflow box with 2 J-tubes on my 55 gallon FOWLR,
<Glad there's two... though, as you'll see if/by perusing WWM, we're much, MUCH bigger fans of drilled through-puts>
which drains into a 25 gallon sump refugium.  I also have an AquaC Remora with the pre-filter box.  In the sump I have a Rio 3100 as the return pump with a 3 ft head.  I also have an old small CPR AquaFuge hooked up in the sump with live rock rubble.
My understanding is that the overflow box is supposed to maintain siphon in the event of a power outage,
<Theoretically, yes>
 but I haven't been able to get it to do so in my testing.  The overflow works great when I start it using just one of the J-tubes (if I try to prime both, one of them breaks siphon and the other keeps running).  I've played around with every combination, inside box as high as possible and as low as possible,
<At least one should be as low as possible. I'd put both thus>
one J-tube primed and both J-tubes primed, skimmer on/off, skimmer prefilter on /off.  Once I pulled the plug on the skimmer and it was able to reestablish siphon right before it overflowed the tank, but I could not reproduce it.  I am wondering if the skimmer and or HOB refugium are causing issues with maintaining water levels in the boxes high enough to keep siphon.  Does that make sense?
<Mmm, your statement does make English sense, but these are not the causes of the overflow issue here. THE cause is the amount/volume of the transit water... from the arrangement (depth) of the J tubes and overflow wall in the overflow, the transit volume is too much for the 25 gallon sump/fuge... try moving the hang on refugium to the main/display tank, and situate the skimmer in the first chamber of the sump... and experiment w/ the minimum and maximum amount of water the sump can hold in the event of a power failure... Does this make sense?>
Any thoughts on how to keep the siphon going?
<Ah yes. Bob Fenner>
Re: Frustration setting up overflow box     3/1/13

Replacing the J-tubes with U-tubes did the trick!
  Now I can unplug my return pump with both U-tubes siphoning and the siphon is maintained. 
When I plug the return pump back in the overflow picks up where it left off.
Thanks for the help!
<Let's hope they keep working. Cheers, BobF>

syphon drains    6/16/12
Hi everyone,
I have written questions and received great advice several times over the last few months about my 120 reef set up, and finally just completed a test run of the piping with tap water...no leaks...but man, is it loud in the sump! And I only have about 400 GPH (Eheim 1260 at 5 1/2 feet) through a single 1.5” bulkhead with a Durso. The Durso is quiet, and I created a make-shift muffler for the drain terminal in the sump to control the bubbles, which seems to be working...but the drain line itself is quite noisy...with the sound of running water.
<Mmm, the Eheim itself should be quiet, unless it's touching the side... The Durso, is aspirated? See WWM re>
 I suspect when I switch to salt water it will be quieter...but searching the internet I again and again find people exalting the virtues of their siphon set-ups for their internal overflows (“Herbie” and “BeanAnimal”).
<Mmm, maybe to/for some folks>
A search of WWM came up with only a couple references and a negative impression of the idea. I am wondering why?
<Their too-easy and frequent (disastrous) failure... loss of siphon... water on the floor>
Based on my understanding, these set ups always have at least one dry/emergency/back-up drain...and assuming this can handle 100% of the pump out-put on its own, without needing a siphon itself, how is this any less reliable than the common 2 undersized 1”drains  systems, or even the single drain overflow units.
<Try it and see; experience will change your mind.>
Seems like it should be very dependable, and with no air in the syphon drain, silent. Sounds great...in theory, and according to numerous “reefers” on the web, though I haven’t tried it yet. I plan to fill with salt water and see how it goes for a while with my standard air-mixed drain line, but wondering why not have this idea as a back up should I desire a quieter system in the future. Why does it seem these set-ups are not recommended on your site?
<See above>
Thanks so much!
<Welcome. Bob Fenner>
Re: syphon drains    6/16/12

Hi Bob,
Thank you for your response!
Could you briefly explain what could happen?
<Mmm, yes... air gets in the line, perhaps a snail or such clogs one/both/all of the siphons... a myriad more>
 I mean if the back-up/secondary drain can easily handle ALL the flow...as in my example, a 1.5 inch pipe with only 400 gph...then the small diameter/valve-reduced siphon line possibly failing shouldn't be an issue.
<Both can/do fail>
 Most of the time it will function properly and be silent. The odd time it might fail the emergency line will take over. Again, I am just basing this on my readings, not experience. What am I missing?
<Just the personal experience Dave. I believe in gravity: It's always let me down. B>

overflow and back siphoning 12/27/11
Wow, am I ever glad I stumbled across your website. A wealth of info for a newbie in this complicated hobby. I have had FW tropicals for years and for the past three years African Cichlids. I am now moving on to SW. I have been reading your discussion forums non stop for about three days now ( well I guess I took time to eat, sleep and go to work)
I have learned a lot about plumbing and realize now that even though my LFS guy is awesome he doesn't have to live at my house with my wife etc and isn't as concerned about overtopped tanks or sumps, as I am. I have a 46G bow front (tempered so can't be drilled) with a prefab sump I would guess to hold about 15 G if it were full of water. It has bioballs in first chamber and Aqueon submersed return pump to main tank plus heater in second chamber. There is some LR and LS in second chamber. Now that I know more I don't think it is good to have LS in with pump even though I built a small open-top enclosure for the pump modified from a five gallon tank to isolate it from the sand.
The sand moves around quite easily and at times goes through the pump.
<Not good, as you state>
My questions involve the hang-on overflow and circulation. The tank runs very, very full, like right at the interior lip with maybe 1/8 inch to spare but it does stay at equilibrium. The height of the water column in the tank makes me nervous as hell, but again it does equalize when the overflow is siphoning correctly. If I turn the pump off and let the water back-siphon for several seconds and then turn it back on it usually comes right back to the high level, but if I mess with it enough I can get it to drop maybe another 1/4 inch. The in-tank chamber of the overflow box is well below the water line, I would say two inches, but it won't siphon and work properly until the water gets to such a high level. If I were to have a PF and the pump quit then a certain amount of water would back siphon from the outflow and from the input pipe into the sump causing the sump overflow scenario. Can I limit the damage by drilling a hole in the input line higher in the water column such that it would break the siphon with air sooner than with no hole if the pump quit running?
<Mmm, yes... but I wouldn't do this... What will happen when the power resumes, if you're not there? Yep, the sump will pump a bunch of water back into the tank, overflowing it>
If so, how big of hole to drill and where (right below waterline?) Then there could conceivably be capacity in the sump to receive the back flow w/o overtopping depending on how much room is available and how much water is back siphoning.
Then my second scenario is tank overtopping. After PF when the pump restarts it will fill the tank but the siphon to the overflow will have been broken by air so the overflow box won't siphon, correct?
<Ah yes>
and then the pump drains the sump and burns up and water overflows the tank until their sump is dry, right?
I did buy the largest battery backup I could find at OfficeMax as a precaution in case of PF when I am not home.
<? In that case, who will turn it on?>
Can a dosing pump tied to the small siphon hose on the overflow box correct this?
<Could... but again, I would not do this>
So what I am saying is, if the system restarts after PF will the dosing pump restart the siphoning action in the overflow box so that the water turnover is re-established at equilibrium?
<Ideally yes>
I guess I don't understand the mechanics of the siphon tube on the overflow box and I have seen the dosing pumps offered as an accessory but not sure how that works. I am just looking for ways to avoid possible overtopping of tank or sump so I can not be so nervous. Do you think I have too much pump volume for the overflow box I am using?
<Possibly... I would settle on just having "not too much" volume in the sump... such that it will accommodate the transit volume... experiment w/ having just enough water to a maximum (in the sump) and mark it w/ an indelible pen so that you remember to never fill it beyond that capacity>
So based on what I am learning, since I cannot drill this tank and provide gravity overflow, I am forced to use hang-on outflow.
If I could do everything the best possible should I:
1) have more than one overflow box?
<Yes, and good quality ones at that... see Glass-holes.com re
2) if so, should they drain independently into sump or one outfall pipe T into the other one before going into sump?
<Either way is fine... best to use a "bag" for this/these discharge/s... see CPR.com re
3) should I have two pumps for backup purposes?
<Mmm, good to have a back up, pre-plumbed, perhaps true-union connectors, to move one pump out, t'other in easily>
I saw where you wrote this is a good idea but I don't understand. Both running simultaneously?
<Not... one in reserve should the other fail>
Would that mean each pump would be 1/2 rated capacity compared to the one larger capacity pump, or do you mean have one handy to be quickly deployed if the first one fails? I am not sure of the physics here with two pumps.
I know this is getting lengthy, but I am here anyway...
4) better to replace bio-balls with LR frags?
<In almost all cases/circumstances, yes>
No LS should be in sump compartment with pump, right?
<Fine if sequestered in an area of low (laminar) flow... as in a few turnovers per hour refugium section>
I have two more tanks to set up after I get comfortable with all of this so I am trying to plan better for the next two.
<Ah good>
Oh what fun!
<Ah, yes>
I definitely want to make sure the next two are gravity systems instead of siphon systems if at all possible. I kind of just let my LFS guy steer me on the current one and I think maybe I could have done it better, or I guess I didn't know all the right questions to ask him. Look how much I have learned already!
<Good! And good attitude>
I have a 90 that I want to make into a reef tank and a 55 for a FOWLR. I want to do like a pair of blue jaw triggers and maybe a snowflake eel in 55, but would that be big enough for the triggers long term?
If not big enough what IYO would you recommend for the 55 just a couple to few larger aggressive to semi-agg fish FOWLR?
A species tank?
In 90 I will do reef safe dwarf angel like coral beauty (I know, not totally reef safe) or, maybe pair of Bellus or Swallowtail Angels,
<Genicanthus need more room really>
clowns, tang and maybe some gobies, damsels and the like. I know I could give the triggers more room in the 90 and make the 55 reef but I thought the bigger tank would be better for reef application due to volume. Your opinion greatly appreciated!! Thank you so much!
Lance in Nebraska.
<Welcome, Bob Fenner in Cal.>
Re: overflow and back siphoning 1/9/12

Hi Bob or lucky crewmember that shall attempt to answer my question(s). I wrote a couple weeks ago about concerns with very high water level in the display tank like almost overflowing 1/8 to 1/4 inch to spare.
<I do recall>
The culprit I believe, now that I am beginning to understand this plumbing stuff better, is hang-on overflow is barely draining fast enough to keep the tank and sump at equilibrium.
I did not add a valve on the output side of the pump so it runs full out 24/7. I wish I knew the GPH, I just bought the one the LFS guy told me. It is an Aqueon submersed in the sump.
<You can look up likely/approximate flow rate based on head, plumbing size, turns...>
Obviously it has no problem pumping a lot of water. So my thought process is this...Add another overflow box (I know they are evil, but can't drill the tank, it is tempered)
<Better to have two than one...>
to hopefully tame the water level in the display tank and provide redundancy in outflow returns in case one or the other were to get clogged. I believe the two outflow boxes should be pretty similar in flow rates. They say 600 GPH. I know you guys say 300 GPH static but it would be more when siphoning is occurring.
<... after all these years, make that decades of doing this, PLEASE believe me that you should NOT count on siphoning. Eventually they fail... air gets in the line, a snail...>
But assuming they are relatively the same flow, if one were to get clogged the remaining could handle all the water if it is currently doing so now with the one existing outflow, correct?
<... hopefully>
And question 2 - since the water level is so high in the tank doesn't it appear that the pump is sized to handle the added redundant outflow when overflow box number two is added?
Addition of box 2 should lower the water level in the tank to something more reasonable by accepting more of the pump flow?
Do you know anything about "LifeReef" Prefilter boxes out of Colorado?
<Only a little>
They guarantee them not to flood, not to fail, to always restart siphon in case of power failure.
<An impressive claim>
Is it true and if so shouldn't I get one of their boxes for my second hang-on?
<Up to you... I'd do a bit of searching, gathering other actual user reviews as practical>
Thanks a ton, this water level thing is making me a nervous Nellie.
<It should... And BTW, w/o the adverb, the name of my late mum>
Wish I would have been turned onto WWM before I jumped into this deal headfirst but I just did what my LFS guy told me. SeeYa!
<Cheers, Bob Fenner>

tank issue while on work trip, and invert deaths... "If it weren't for bad luck..." 12/8/11
While I was on a work trip and my wife and daughter were maintaining my reef tank, I had a failure with the overflow unit. The overflow stopped functioning and water ended up all over the wife's hardwood floors.
They shut the overflow pump off and also killed the canister filter that I had on the tank as well.
The issue with the overflow was the vacuum pump that was working with the CPR-90 overflow unit died.
<Do write them re>
Hooked the air line to a MaxiJet and it started suctioning again. The canister filter issue was the wife knocked off the inlet line.
It was vibrating loudly with barely any water going through the unit.
<Until it failed>
When I came back, there was a massive hair algae and bristle worm explosion.
<No thanks>
Also, some of my inverts, corals and anemones started dying.
I lost so far:
1 small anemone (not sure what type it was, but it was small, and blue with long tentacles)
1 frogspawn coral
1 cleaner shrimp
5 or more hermits
1/4 of my snail population
1 large rose long tentacle anemone
All the bristleworms (they are piled up just sitting in the open) I am going to take pictures.
<Best just to vacuum the worms out and toss>
Here are my specifications:
75 Gallon tank with 20 Gallon sump Water tests using a strip showed 0 nitrate, 0 nitrite, 7.9 PH I did about a 40% water change as I ran out of RO water, and have to fill everything back up. All fish appear healthy.
To make a super long email short, is there something that would affect inverts, corals and the anemones, but not the fish?
<Mmm, yes... likely some of the Cnidarians produced a "cascade event" of chemical allelopathy here; of something/s more toxic to invertebrates than fishes>
What should I test for additionally?
<Mmm, the compounds involved are not w/in the test repertoire of hardly anyone... Are you an organic chemist or engineer? If not, I'd search on WWM re the term string above, keep doing water changes, and possibly use chemical filtrants>
I am trying to save the tank.
<Welcome. Bob Fenner>

Silly Plumbing Parts Question/Plumbing 9/9/11
Good morning, crew.
<Hello Dustin>
Have kind of a silly question this morning, as I'm looking for a piece of terminology that has eluded me. I'm buying a drilled 40g, and know I need to replace the bulkhead; but it is also lacking the overflow "barrier":
the internal wall separating the overflow from the rest of the display.
Having a military background, I kind of thought that this would be called the bulkhead (just means "wall" in Military-ese), but a search for that just gave me the fittings for the drilled spots. Is there actually a term for this and/or a retailer where they can be purchased, or will I likely have to construct one myself?
<First, where are the drilled holes located, and what size are they? Oh, and incidentally, they are called internal overflow boxes.>
Thanks Crew,
<You're welcome. James (Salty Dog)>
Silly Plumbing Parts Question/Plumbing 9/9/11

Thanks for the quick response, James.
<You're welcome.>
The hole (singular, but that's fine since I'm just going to run the return behind and over the tank) is about 1-3/4" (have to double check with the seller on this) and located in the back right corner of the tank...hopefully not too far in the corner,
<On the bottom of the tank or side of tank?>
or the stand I'm building will
have to have a cut-away in the frame to accommodate the plumbing.
<Thinking bottom of the tank now. Would be quite easy to construct a corner overflow box just by siliconing a piece of glass against the corner and make a weir/comb out of acrylic which you could
glue to the top of the corner glass.>
I know from reading your sump and plumbing section that a hole this size usually serves a 1" bulkhead, generating a rate of flow between 300-400 gph. I've found the link on WWM regarding pumps and their ratings, so I'll be using it a s reference.
As far as using gate valves, T-fittings, back-siphon failsafes, etc, this is all new ground to me, so I'll be reading a lot in the next few weeks and bouncing some questions off of the reliable LFS employees I know that do custom commercial and in-home installs.
<Ditto. James (Salty Dog)>
Re Silly Plumbing Parts Question/Plumbing 9/911

Dustin, and before I go further, please reply to the original thread when replying back to
us. We receive many queries per day and it is difficult to remember details of what was said or
recommended for each and every query we receive.>
You got it, the hole is drilled in the bottom of the tank. And after looking around a bit, I think I'll got with some acrylic to make the internal overflow (I'd prefer something opaque, so you couldn't see the standpipe...though I suppose a little aquascaping could help hide this as well).
<Sounds good, the glass was only a suggestion/idea of what could be done.>
I've also found Richard Durso's page and his personal approach to using a standpipe with a submerged intake. I'm going to give it a shot (the tank is in our living room, and the gurgling would otherwise drive my wife insane).
<That is exactly the reason I have learned to drink beer without making gurgling sounds.>
As for the sump, I'm just planning something simple. I've got a CPR SR3 that I'm taking out of my BC 29 (converting to a freshwater planted in the long run, outfitted with 4 Edison opto 6 LED strips, 2 6500k and 2 455nm), but I'm keeping the stocking list pretty small: 2 Tomato Clowns (about 2-1/4" in length) and their BTA (not an ideal size for her, but better by far than the BC), a yellow watchman and its pistol shrimp, and my Coral Beauty (so long as he and the clowns continue to get along).
<Down the road, a 29 will be a bit small for keeping two Tomato Clowns.>
I was planning on having the overflow empty through a filter sock to catch large
debris, and go immediately to my first chamber with the skimmer.
<Good plan, do clean the sock weekly.>
I'm still debating on whether or not to do a middle sump chamber as a refugium (I do keep a small Stylohpora colony, a Trachyphyllia, and a few Zoa's, but didn't know if the biological diversity in a 'fuge would benefit them).
<I wouldn't mix Zoas with corals in that small an area.>
At any rate, my real debate is whether to structure the middle chamber with LR rubble, then drop in a bag of carbon on its way to the return, or do a DSB with the LR rubble and some macro algae. Oh, and as the tank is pretty shallow to begin with (it's a breeder), I was only going to attempt a SSB in the display for aesthetic purposes, maybe 3" to accommodate the pistol shrimp and my Nassarius snails.
Any thoughts on how either option would benefit my tank? Am I opening door to more possibilities with a refugium, or just creating more maintenance?
<At this stage, searching our site will provide many answers to your concerns.
Our marine index can be found here.
<You're welcome. James (Salty Dog)>

Filtration/Overflow Boxes 3/14/10
Hi guys,
<Hello Clint>
I've got a question about the filtration system on my marine aquarium that I hope you can answer for me.
<Will do my best.>
My system is a 75 gallon aquarium with roughly 125lbs of live rock that is filtered by a SeaLife Systems pro series sump with a built in, yet removable skimmer. The tanks inhabitants are a pair of clowns, a Six Line Wrasse, a Coral Beauty angel fish, a pink and blue spotted Watchman Goby, and a Scarlet Cleaner Shrimp. The coral inhabitants are a mushroom rock, a colony rock, a Candy Cane Coral, a Brain Coral, a Bubble Tip Anemone, and a frag of a Branching Hammer Coral. Unfortunately my tank was not a reef ready tank so I have an overflow box that drives me nuts.
<I'm not very fond of them myself, but I do like the CPR units.>
I've had it for over a year and so far it hasn't failed but it seems like everyday I'm having to vigorously shake the overflow tubes to remove air bubbles.
<Mmm, must be taking in air, otherwise should not happen, not daily anyway.>
I also have concerns about the skimmer as it doesn't seem to remove very much waste. By very much waste, I mean that I can go about a week and only have roughly a quarter of an inch of waste in the collection cup. My
question is that do you feel with the amount of live rock I have that I could have a more efficient, less hassle system if I removed the sump and installed a more efficient skimmer like the hang on Remora Aqua C along with a power filter (for carbon usage and water movement) and a powerhead?
Your expertise will greatly be appreciated.
<Sumps are a great way for air and CO2 exchange in a system along with providing a place for your heater and protein skimmer. I would only go the other route as a last resort. You may want to get a better designed overflow box to eliminate most, if not all of the air bubble problems you are having. You may want to look at the CPR models that use an air pump to prevent bubble build-up in the siphon.
Premium Aquatics has better prices on these units and the air pump, but the link I provided has more downloadable information on these units.
But to answer your question, you do have enough live rock to provide good denitrification of the system without using a sump.>
<You're welcome. James (Salty Dog)>
Clint G.

Overflow Box (for undrilled tank) Overflow box selection and design 8/8/2009
<Hi Andrea.>
I should begin - the tank is not drilled and I'm afraid I really am not in a position to do that now due to the massive rock structure I have on the back wall.
I can see you guys are no big fans of these overflows but it is what I am limited to. I am aware of the pitfalls and am quite pedantic at cleaning / maintenance.
<I use them myself, as my tank is not drilled either. They are fine as long as certain precautions are taken.>
I started my system with the AquaOne MariSys 240 and am ready to upgrade my sump/refugium/skimmer etc. Big problem - the overflow box that comes with the MariSys has been set quite snuggly within my rock wall and the available off the shelf designs will not fit.
I have also read enough now to want to move away from the channel style OFB (MariSys / CPR / Reef Octopus etc) and go with the U tube design.
<That is the design I have and am quite happy with it.>
The one I have decided on (based on feedback and general positive comments I've researched) has been the LifeReef design.
This is the link to the LifeReef website - product pages will outline their pre-filter boxes.
I have read nothing but good reports on these OFB's. I will contact them to see if they can make me this one but I'm thinking the shipping to Australia is going to be a killer and then what if something doesn't fit?
<Wouldn't worry so much about shipping, but fit could be an issue. I would provide very accurate measurements of how large you want it, and then as an added precaution, give him a tolerance measurement: i.e. 100mm +\- 1.5mm >
I'm having nightmares thinking about all the drama I could encounter dealing with a company on the other side of the world.
<In the days of internet, cellular communication, and next day shipping, it is not nearly as difficult as it once was.>
I'm pretty sure I could get it fabricated here. To me the idea looks pretty straight forward in terms of acrylic work.
<True, nothing too difficult about it.>
When I built my rock wall (made with black foam / dried coral rock etc) I was working around the MariSys inner box not really thinking I would ever want to replace it.
<Hehehe, the only constant is change.>
As you can kinda see in the pic below - its all pretty tight room wise.
It's ugly too (see attachments Plus a link to Photobucket)
<Hmm, not too bad, You could go with clear acrylic in the tank and it would vanish a bit better.>
I've tried to put something together that works with the size limitations - more reliable and not so intrusive visually.
<I cannot see any glaring faults in your design except if your sump permits it, I would have two drain lines rather than one, and also if possible, I would use something larger than 1' (25mm) 1.5" or 2" (38mm and 50mm respectively) would offer much more flow than a 25mm line will. It will also be significantly quieter. Do read here:
http://www.wetwebmedia.com/plumbingmarart.htm >
I also wanted to add a lid/cover to slow some algae growth in the siphon tube. If its too noisy, there's a good DIY site that has a silencer for these OFB's.
<A lid would be a nice addition.>
The problem I have is, I'm not sure if I've left out some crucial detail in terms of 'workability' in terms of basic siphon principles? I get the basic idea (in theory) the U tube should remain full unless it accumulates
air bubbles.
<Yes. I would also add a second tube just as a safety measure.>
This design with adequate flow (rated at around 2400L/h) should work well with the AquaBee 2000I return pump I plan to run in my refugium What I am not sure about is how critical the height of the divider in the outer box needs to be set at?
<Divider isn't really necessary, it may help abate some noise, but I would be in favor of having it lower rather than higher.>
Likewise, the U tube setting height wise etc.
<In as far as it will go, so both ends are always completely submerged.>
Likewise in terms of the inner box ---- (there is an adjustable butterfly nut to set the height but other than that, is this the only method of setting the water level inside the tank?
<There are other, more complicated methods, but the butterfly works just fine.>
As you can see, I've drawn in the absolute maximum water level and the heights at which my tank trim comes up.
<I see this. Very nicely detailed drawing.>
I was wondering whether you have anyone there that has some intimate understanding of these overflows to see whether there's anything glaring that raises a red flag?
Other than what I've mentioned above as possible improvements, I see no fundamental errors in the design.>
I plan to run a float limit switch that will cut the return when the sump gets below a certain level to help safeguard a blockage.
<A nice addition.>
Thank you for your wonderful reference site --- I have had a really good search for this info both on here and other forums / Google etc but am alas turning to you for some guidance.
<Happy you found it helpful.>
Kind Regards
<My pleasure.>
Andrea - South Australia
<MikeV - Central Florida.>

Overflow Boxes 7/21/2009
Super site!
<Glad to hear you find it helpful.>
I am new to the hobby/addiction and have a one month old reef setup in an older glass 150 g H tank that is NOT pre-drilled and does NOT have an internal overflow.
Currently I am running Nova Extreme T5/Lunar lighting, Rena xP3 canister, a CPR Refugium, and I want to put my protein skimmer in a 40 gal sump tank underneath but am really unsure of how to safely pull water down to the sump and then return it at the same rate so that I do not overfill either the reef tank or the sump. Please advise!
<The only guaranteed way for the water movement to occur at the same rate is to use a pump to pump water to the display tank, and a overflow box to bring it back down to the sump. Please search for "overflow box" on the website and read up. Let me know if you have any questions after you research it.>
Also, can I effectively/efficiently replace the bio-balls in the sump with live rock instead as I have about 100 extra pounds of LR at my disposal?
<Certainly, and this is likely a good move. I suggest removing the bio balls a small amount at a time, maybe a third at a time. After each stage of removal allow sufficient time for the other beneficial bacteria to catch up with the bio load of the tank.>
<Your welcome.
Josh Solomon>

Multiple HOB overflow boxes 5/13/09
I just bought a 210g glass tank. Drilling is not an option.
<Why not? I assure you it is!>
I have 2 Eshopps pf-300 Overflow boxes laying around. Is it safe to have 2 running on the same tank?
<Tis the way to do it. Have the return pump flow what only one can handle, that way the second is purely for redundancy. Scott V.>
Empty your mind, be formless, shapeless--like water.
Now you put water into a cup, it becomes the cup, You put water into a bottle, it becomes the bottle,
You put it in a teapot, it becomes the teapot.
Now water can *flow* or it can *crash*!
Be water, my friend.
-- Bruce Lee

Re: Multiple HOB overflow boxes 5/15/09
Ok here is the problem, the Eshopps PF300 is only rated at 300GPH.
<An honest rating.>
Is there anyway to increase the GPH?(bigger drain, bigger UTube?)
<The drain size is the issue. I do not believe there is sufficient room to install a larger one.>
My tank is a 210g and I want to get at least 1200gph. I'm thinking since I already have 3 of these overflows I can buy 1 more and run 4 of them, 2 on each corner of the tank.
<It is what you need to do if you are not drilling. But do consider one of their larger units, one with the 1.5" drain. You don't want to run these boxes to capacity, you want to have extra draining capacity should any one of the boxes fail. Scott V.>

Need an Expert Opinion--Sump/Overflow 10/20/08 Greetings, <Jason.> First I can't say enough about your website, it truly is a gift. <Thank you.> So, I have a 60 gallon FOWLR with only a few fish (mated tomato clowns and a blue damsel). Also have plenty of live rock (don't know how to estimate weight) and about a 3-4" deep sand bed. Currently I have 2 Hydor Koralia's for circulation along with a BAK-PAK 2R protein skimmer and a CPR Hang on Refugium. My wife and I are looking for a "more attractive" solution. So we've purchased a CPR CY 192 sump/skimmer. Our tank isn't pre-drilled. So, I've purchased 2 300gph Eshopps overflows to flow into the sump via a T into the sump. Then I have a Mag Drive 7 to pump back into the main tank. I guess my question is, what is the appropriate way to set up the flow so that my overflow boxes are truly redundant? <Limit the flow of your pump to what one of these overflows can handle, leaving the capacity of the second for 'just in case'.> For example, if one goes out, how do I make sure the other one can pick up the slack without overflowing. <Limit the return to 300 gph.> Another question, and this one may be stupid, with two 300gph overflows is the effect additive, so the resultant would be 600gph? <Yes, at a maximum.> I know it may not be exactly that given resistance in the pipes, etc. Any other criticism or ideas/modifications would be helpful. I know that no overflow system is 100% safe and that regular maintenance will be needed to keep it running to it's best. So I'm looking for a "safe as can be" system. <A drilled tank is safer, but if you do limit the flow and keep one overflow as a backup you will be fine here.> Thanks and keep up the good work. <Will do, thank you.> Jason Wake Forest, NC <Scott V. Fresno, Ca.>

Re: Overflow/Plumbing Question 4/23/08 Scott, A few last questions if you don't mind. <No problem.> For a redundant overflow box for my tank (knowing what I already have), what size do you recommend? There is an Eshopps PF-800 single intake (800 gph) for up to 125 gallon tank, the Eshopps PF-1000 dual intake (900 gph) for up to 200 gallon tank, and I found one on eBay made by CFL Aquatics that is a dual intake 1200 gph model. Do I need a dual intake, or can I get by with a single intake 800 gph? <A dual intake would be better for redundancy's sake even within the one box.> One thing I'm a bit worried about in sizing this up is this--will adding a second overflow necessarily increase the volume of water that flows into my sump, or is it only that my system is now capable of delivering more flow to my sump (is this just a question of what goes in can only do so as fast as it goes out?). <You are increasing your flow capability. If you do not increase your sump return output you will not increase the actual flow.> My reason for asking is, if one overflow box fails and your pump is putting water back in the tank faster than your redundant box is capable of handling, what happens (I know the answer)? <Yep, water on the floor. The idea of redundancy it to flow what each box can handle should the other box fail.> I guess my question really is, how do you know that your return flow is never more than what any one of your boxes can handle? <Pump ratings and knowing what your boxes will actually flow (not what the manufacturer claims) is a fair estimate. The only surefire way is to try each box one at a time to actually see if it can handle it. This can be pain, but you only have to do it once.> I do intend to purchase a level controller that will kill my pump in the event the tank starts to overflow. <This is really not needed with overflows setup as discussed above, but an interesting idea towards an extra safety check.> Thanks again! Andy <Welcome, Scott V.>

Overflow Question (External Overflow Box) -- 04/16/08 Hello, <<Howdy>> I'm in the planning stage of starting a salt water aquarium. <<Ah! One of the more exciting aspects'¦along with building, stocking, watching, enjoying'¦aw heck, it's 'all' exciting!>> I want to go with an acrylic tank as it seems to be easier to modify with DIY projects without having to worry about the glass being tempered and whatnot. <<Tis true'¦though both materials (glass and acrylic) have their virtues'¦and downfalls>> Anyways, my question is about the overflow. Every design I've seen or read about uses either unhidden bulkheads in the back/bottom or some sort of cover using vertical teeth routed in the acrylic. What are your thoughts about a horizontal hole routed in the back of the tank draining into an external overflow box? << By 'horizontal hole' I assume you mean a 'slot' routed horizontally along the panel. I have seen pictures of such installations'¦and came VERY close to going this route I was building my own system, but being an in-wall installation, I just didn't have the needed clearance around the tank. And to answer your question'¦ With some thought to design and construction, I think an 'external' overflow is a fine idea>> If I used say a 3/8" router bit, would that be a small enough gap to prevent critters from getting out of the tank? <<3/8' is larger than you need'¦I would be inclined to go with ¼' or even 3/16' depending on the length/number of slots>> What sort of water flow through that hole could I expect if I made it say 1 foot long? <<The 'area' of a 3/8' slot that is 12' long is about 4.5''¦almost as much area as a 2.5' hole. I would think this would allow a 'safe' gravity-flow rate of some 1600gph or so. Even a ¼' slot of that length still has an area of 3''¦which is just under the area of a 2' bulkhead>> In my search I found only 1 post that really addressed this sort of setup and the criticism focused on the possibility of the box falling off...presumably on a glass tank. On acrylic, it is essentially welded on correct? <<If done correctly/well, yes'¦the molecules of each become 'mingled' and the two would become one. And this is reason enough to do your research/homework before attaching the overflow box since any attempt at removal to correct a mistake will require machining the box off>> My main reason for wanting it this way is so I can just sink a pump in the overflow box for a closed-loop and still have room for a couple drains down to the sump. <<Faulty logic here, mate. Aside from the inherent balancing problems here of 'sharing' water/applications'¦placing the pump in the overflow box does NOT constitute a 'closed-loop.' This would be an 'open' system'¦and to properly 'power' the return manifold would likely require flow rates that would be impractical to this application. Another problem with this design is if the return pump were to fail/stop while the pump in the overflow is still running, the water will drain below the overflow and result in damage to the other pump>> This hopefully would give me a high water circulation rate for the tank without the noise from running all that water all the way down to the sump and back while still avoiding an unsightly intake tube in the tank. Thoughts/Ideas? <<The idea of an external overflow for a sump-water return system is fine, in my opinion'¦and can even be utilized with a return-manifold if you like'¦but the high flow rates needed and expected for a true 'closed-loop' application (e.g. - minimum of 650gph for EVERY ¾' nozzle) make it, or any type, of gravity overflow impractical for this use in most home applications. A closed-loop requires a 'dedicated' water supply line>> Thanks, Ryan <<My pleasure to share. Eric Russell>>

Re: Overflow Question (External Overflow Box) -- 04/17/08 Hi Eric, <<Hello, Ryan>> Thanks for the advice. <<I hope it was of some use>> I guess a little clarification is in order. <<Yes, please'¦and thank you for this>> I am currently planning on getting a 60G 24" cube. My closed-loop plan is really a 2 outlet SCWD hopefully providing around 10-15 x turnover while my return pump provides around 5x-ish (3-5x through the sump is what I've been reading right?). <<Yes>> The overflow box would have Durso standpipes so the water would drain from a higher elevation and not the bottom of the overflow box (assuming the pipes/bulkheads don't fail). <<Ah, okay'¦so the pump for the loop would be positioned at the bottom of the box well 'below' the water-line. Hmm'¦>> I would make them high enough that the SCWD pump was permanently underwater even if the return fails. <<Yes, I understand now'¦ You might be able to pull this off. But'¦do keep in mind that the SCWD pump will continue to circulate water through the overflow box when the sump pump is off'¦if the standpipe drain level is 'lower' than the slot through which the water feeds to the overflow box, water will continue to drain to the sump (or on to the floor if the sump doesn't have room for the extra capacity!) until the level in the tank no longer reaches the slot'¦once this happens, the SCWD pump will pump the overflow box dry, possibly resulting in damage to the pump. Constructing the box and standpipes such that the 'working' water height is above the feed slot should resolve this issue'¦but that means the water going to the overflow box won't be 'skimmed' from the surface. Another option is to provide slots at both the top and bottom of the overflow box (much like many commercial internal units are fitted). This would allow surface water to be skimmed to go to the sump, yet also allow the overflow box to remain 'flooded' when the sump pump is off>> I guess my main fear is that if the SCWD pump were to fail/leak it would already be in a wet zone and not draining all over my floor. <<Tis true'¦but with well constructed 'hard' plumbing and a quality external pump this is of little concern, in my opinion>> I've got a pretty serious wood shop in my garage and don't have much worry about cutting and building the overflow box to tight enough tolerances (after a little acrylic gluing practice). <<Ah! Excellent'¦ (I built my shop off the back of my garage'¦the Mrs. was tired of parking in the driveway [grin])'¦and I do like having 'heat and air'>> My main concerns with the length and width of the slot would be to keep critters out while providing a diffused suction zone <<Yes>> ...also how far from the top of the tank should I make it (If I go this route) to maintain the structural integrity of the back wall? <<This is a good question and a valid concern'¦and I do wish to make known/reiterate that I haven't actually built one of these systems myself. But of the few designs and pictures of working systems I've seen, the exact position of the holes/slots in relation to the height of the tank didn't appear to be much of an issue'¦though I must say these were new setups so I don't know what the long-term effects have been. The height/position of the slot(s) should be determined by your desired working water height in the display. But of more concern here to the structural integrity of the tank than the position of the slot is the 'length' of the slot. I would suggest cutting a series of shorter slots whose 'combined' length will provide the desired flow capacity, leaving a small web of material between each slot'¦in other words instead of one 12' long slot, cut three 4' slots leaving a 1.5' space between these. Also'¦make sure the ends of each slot are round (circles) and not squared-off else stress fractures will likely occur (drilling the appropriately sized hole at each slot-end and then 'routing' from one hole to the other makes this a simple matter). Cutting the series of shorter slots will still give the same overall flow capacity of a single longer slot, but the intact material between each will yield a stronger structure. Do also consider that the attachment/solvent-welding of the overflow box to the outside of the back panel around the slot cutouts will also afford some structural integrity to this location (I would be inclined to use at least ½' material for this). You might also consider adding a strip of acrylic the width of the tank and overlapping the slots by a couple inches top and bottom to beef-up (double?) the thickness of the tank wall in this area for more strength (I would add this first and then drill and route the slots through the beefed-up panel). This may all sound like overkill'¦and I do always tend to 'over-engineer' my projects a bit'¦but it helps me sleep better'¦ [grin] >> How close to the sides do you think I can safely go? <<It may be a moot point with the previously mentioned considerations'¦but still'¦I would leave an inch or two of clearance here>> If it's a 24" back wall could I get away with an 18" slot? 20"? <<Depends'¦and will take a little calculating'¦but the 'total' slot length will depend on the size and number of individual slots, while taking in to consideration the needed clearances between these and the sides of the tank. But whatever you come up with'¦my recommendation is to make no single slot more than 4' in length and to maintain a minimum of 1' between slot-ends and side-walls>> So with your previous numbers I should safely be able to expect around 1600 gph which is just shy of 27x flow. <<For 3/8' slots that measure 12' en toto, yes, the math would seem to bear this out>> If I shoot for 20x turnover total I should have a margin of safety. <<Now you're thinking! [grin]'¦ Always best to allow for extra/not to 'max-out' flow capacity>> Is it enough? <<Probably'¦but is best determined by the species/apparent health of the organisms kept>> I guess to be really safe I should have the capacity for double whatever I plan on eh? Around 35-40x. <<If practical to accomplish>> Thanks, Ryan <<Happy to assist, mate'¦do please keep me in the loop on this, I am very interested to know how this project goes. And if you wish to discuss more'¦you know where to find me. Regards, Eric Russell>>

R2: Overflow Question (External Overflow Box) -- 04/19/08 Hello Eric, <<Morning, Ryan>> Here are some pictures from Google sketchup of my plan so far. <<Ah, great!>> I included the actual sketchup file just in case you use the program too...as I imagine many do nowadays. <<Mmm'¦have not used/seen this>> The box inside the overflow is the dimensions of a Mag 9.5 pump. <<Okay>> The dual thickness acrylic over the slots does look to be overkill to me. I think the bottom of the overflow box welded to the back of the tank along with the top flange should brace that area enough without...thoughts? <<Maybe so'¦though it may still 'bow' some. When I made the recommendation I was envisioning an overflow box that extended to the bottom of the tank with slots near the bottom where weight against the panel would be the greatest. Looking at your diagrams, it seems to me that your overflow box is too shallow. Aside from making sure the box has enough 'volume''¦you want to allow some room above the standpipes for fluctuating water heights within the box due to restrictions/changing flow rates in the drains. Especially with that circulation pump pulling water in to the overflow chamber; a slight restriction in a drain line (even if only from the natural build-up of organic-material/secondary settlers on the lining of the pipes) can put a lot of water on the floor in a hurry if you haven't allowed some room re. Do also consider that extending the box will increase overall volume of the system. You don't have to go the full height of the tank'¦but I would certainly go larger than you have illustrated>> I would like to narrow the overflow down a bit so the tank is a little closer to the wall if possible. <<This, as I'm sure you are aware, is limited by the size of the circulation pump residing in the overflow chamber>> Also, I think I need to move the bulkhead holes around a bit. <<A consideration'¦ If using 'Durso' style standpipes you will need to allow room/space between the bulkheads for the bend at the top of the standpipe'¦utilizing a 'Stockman' style standpipe will allow less room betwixt the bulkhead fittings>> Ryan <<Regards, Eric Russell>>

Wanted to Share Positive Experience with Recommended Vendor... 12/06/2007 WWM, <Hi Paul, Mich here.> I just wanted to share a very positive experience with a vendor that you pointed me towards - glass-holes.com. I have no affiliation with them, other than being a satisfied customer. <Very good.> I was looking for internal overflow box for 120g tank, and you suggested I take a look at their website. Mike and the crew at glass-holes.com talked to me a number of times via email and telephone (yes, telephone - nice, personal touch) to help me figure out exactly what I needed. They even called the wholesale-only manufacturer of my tank and talked to the tank builder to find out if the rear wall glass was tempered or not (the manufacturer does a good job of hiding its contact info from the general public... been a while since a Google search was not productive....). <Resources are good.> The overflow box they shipped to me was custom ordered and the workmanship was flawless. To anyone comparing overflow boxes built into tanks by the manufacturers vs. something like I got - there is no comparison. No cheap, thin black plastic used. It is 1/4" acrylic, beautifully crafted. The bulkheads supplied are nice and thick (reminds me of the spa jets I put in - thick and sturdy to stand up to high pressure and heat of a 2hp Pentair pump and 400,000 BTU heater). The glass drill bit worked perfectly, and their website had helpful hints that really took a lot of fear out of a DIY project that might make a few queasy (i.e. drilling a glass aquarium). Heck, they also included a t-shirt (I know...free advertising/marketing... but custom t-shirts still cost a couple bucks to produce). <Yes, both potentially win... that is if you wear the t-shirt.> You can't beat the prices...about 1/3 to 2/3 the price of the other two custom manufacturers I could find on the web. Their drill bits are the cheapest I could find, and their bulkhead/plumbing prices are very reasonable. All in all, the folks at WWM should feel more than comfortable sending people over to glass-holes.com. They will treat your viewers right. <Thank you for sharing your positive experience. I'm sure it will benefit others as well.> Paul <Cheers, Mich>

Quietflo Hurricane overflow 9/13/07 Hello Crew: First, thanks for all of your hard work. Collectively you are one of the top resources on the web. (I think that's high praise, so I hope you do, too!) <Indeed> I have searched your site high and low for an answer to this question, but have come up empty each time. Do any of you have any experience with the Quietflo overflow box manufactured by Hurricane filters? <I do not... but see it here: http://store.hurricanefilters.com/quprov.html> I am obviously in the market for an overflow box and am deciding between the LifeReef, AMiracle and the Hurricane Quietflo. I know (via your site) Lifereef's reputation for quality, but am balking at paying $200 for a double box. Hence the Quietflo--it utilizes the same design as the Lifereef, but is less than half the cost (~$75). The pictures I have found make it appear that the quality is good, but I don't feel comfortable judging by their pictures alone. Any help would be greatly appreciated, and thanks again for all of your hard work! Sincerely, Mike Delcomyn <Well... I and a few others here are not fans of such hang on technology... as opposed to drilled/gravity overflows... I would definitely get/use two if going this route... to avoid flooding should/when the one fails. Bob Fenner>

Sand In The Overflow Boxes? -- 07/30/07 Hello, <<Howdy>> I am setting up a 135-gallon Oceanic "Reef Ready" aquarium with their standard overflows/returns in the back corners. I am planning on plumbing the 1" holes with Durso standpipes and the 3/4" with returns. <<Mmm, okay...will achieve an optimum turnover of about 600gph or so>><RMF would say "maximum" rather than optimum> Would there be any advantage/problem with dumping six-inches of sand at the bottom of the overflow around the pipes? <<I wouldn't...will make it exceedingly difficult/messy to service/remove/reinstall the overflow/standpipes should the need arise>> I'm new to this stuff but it seems like every bit of filtration helps and the space seems, while not huge, not insignificant (or maybe it is!). <<Would have little impact re Nitrate reduction I think...not worth the hassle>> I really love your site. <<Thank you...a collective effort>> I feel fortunate to have found it in time. I was in the process of jumping into this too quickly without enough thought and planning. <<Tis indeed fortunate then>> I now spend my free time reading mainly your site, some other internet sites (esp. Reef Central), and books recommended by you (Love the CMA!). <<Is always best to research/obtain information from more than one source>> It is more complicated than I originally thought, but exciting! <<A wonderful hobby, agreed>> So much to learn, so little time........ <<Mmm, not so... Now 'is the time' to make/take the time to learn it/do it right>> Thanks, GaryC <<Regards, EricR>>

Hang-On Overflow Noise (Water Volume vs. Pipe Diameter) -- 05/14/07 I just upgraded my 29 gal reef to a CPR100 overflow and draining into a 10 gal sump. I decided to hard pipe the overflow in with 3/4pvc and two elbows. No matter how I position the straight down tube into the sump sock I get the constant sucking and releasing sound in the box. <<You are likely trying to push too much water through the overflow. The 1' bulkhead that comes with the overflow will only handle about 300gph (yeah, I know they are rated for more flow...just not practical), by reducing the output diameter to ¾' as you have done with the PVC pipe you have reduced the flow capacity even more to about 150gph or so...which is more than enough, by the way, for this tank/sump combination in my opinion>> Will the Durso pipe solve this problem of noise? <<I have seen what looks like a modified/compact version of the 'Stockman' standpipe for hang-on overflow boxes (see here: http://www.aquariumlife.net/projects/diy-overflow/74.asp), but whether or not it will help is probably a matter of trial and error. It may help smooth flow a bit but if you are getting a surge effect as you describe you will probably have to back off on the pump output from the sump (easily accomplished with a gate-valve plumbed in-line after the pump)>> Even if I put the sump pipe under water it still makes and ton of noise and I am really trying to understand this problem. I want the tank to run with the least amount of noise as possible and the splashing in the sump will be easy to fix if I can get the overflow to stop sucking and making gurgling noises. Any other suggestions? Thanks. Will <<Definitely sounds like a case of too much water volume coupled with a too small throughput diameter to me. Regards, EricR>>

Re: Hang-On Overflow Noise (Water Volume vs. Pipe Diameter) -- 05/15/07 Question regarding the 3/4 PVC. <<Ok>> I am trying to get some clarification on what sizes I have used. <<...?>> The 1'' bulkhead accepts a schedule-40 3/4'' connection piece and then goes to 1" elbow. <<Mmm, no...the 1' bulkhead will utilize 1' pipe/fittings...a 1' ell will require 1' pipe. If you have used ¾' pipe then you either have ¾' fittings and bulkhead, or you have use 1' to ¾' reducer fittings>> I noticed that the 1" PVC pipe is the same size as ¾' fittings. <<The outside diameter of 1' PVC pipe is very close to the outside diameter of a ¾' PVC fitting, yes...but in no way are the two compatible without the proper reducer fittings>> Why is this. <<The ¾' fitting must be large enough to fit around the outside diameter of the ¾' pipe...and a 1' fitting for 1' PVC pipe is noticeably larger by comparison>> Basically I am saying that 1" pipe fits in 1'" bulkheads but the 1" is really ¾' in order to fit in that space. <<No...>> This is confusing to me and makes me wonder what size I hard piped mine in with. Please advise. <<If you used 'all' 1' PVC fittings and pipe then figure your flow based on a 1' diameter drain...if you used ¾' pipe or fittings (even just one) in combination with the 1' PVC pipe and fittings, then figure your flow based on a ¾' diameter drain>> Also my Mag 5 with head pumps about 300 gal/hr and I was wondering if the gate-valve would be alright to use to restrict flow from the pump? <<Absolutely...the way these magnetic pumps are designed/work makes them very compatible for use with a gate-valve for tempering flow>> Thanks for your help. Will <<Happy to share. Eric Russell>>

Overflow Box Pump... Bizarre ap.? 5/21/06 Good Afternoon WWM Crew! <Good morrow Josie> I have a question about Tom's Aquatics Aqua Lifter - Dosing Pump and Tom's Aquatics Aqua Lifter Suction Pre-Filter. < http://cc.msnscache.com/cache.aspx?q=3240008336083&lang=en-US&mkt=en-US&FORM=CVRE> I brought these to maintain the flow through the overflow box. <? How?> I had a Toms Aquatics Aqua Lifter - Dosing Pump already, but it was beginning to go out and didn't provide enough flow for the overflow box to keep water flow, so we decided to get a new one. Well, we find out that you should use the Tom's Aquatics Aqua Lifter Suction Pre-Filter in addition to the Aqua Lifter - Dosing Pump. The problem is, there are no directions for installation so we just did what we thought was correct. We had the middle connector of filter to the intake on the pump. Then the outside was attached to the overflow box. The problem is, when we did this, the flow in the overflow box decreased significantly. I did notice that the prefilter is pulling stuff out of the water, so I do believe that it is doing what it is supposed to. It is also still keeping the overflow box primed but the flow is very low. Can you tell me if I am doing this right or is it supposed to be a slower flow? <... I don't think this gear is useful here... in this application. This is a dosing pump... and an in-line filter... not intended for recirculation... or any attachment to an overflow...> It is quite loud with the Pre-Filter attached as well. It's almost as if there is air in the filter or something that it can't clear out. Any suggestions?? <... Contact Tom's and ask them... And read here: http://wetwebmedia.com/marsetupindex2.htm Scroll down... read re Marine Plumbing, Overflows...> By the way, the lionfish that I wrote about a month or two ago is back to not eating. It's almost as if he is starving himself on purpose. We still add trace minerals to the water to prevent lock jaw again, but this time it's different. He shows zero interest in food. All the other fish in the tank eat as normal and all seem quite healthy. We have tried multiple times to hand/force feed the lionfish. We try daily with no results. I have read that sometimes lionfish do this and starve themselves to death. Thanks much! Josie <See elsewhere on WWM re Lionfish Foods/Feeding/Nutrition. Bob Fenner>

Online Source for Internal Overflow Boxes - 6/10/06 Hello, <<Howdy>> I have a quick question, I have a 150 gallon drilled glass aquarium and I need new overflow boxes and I can't seem to find a place to get them. Can you give me a website to buy them from? <<Sure! Have a look here: http://www.wetdryfilter.com/internal_overflow_boxes.htm >> Thank you for your help. <<Welcome, EricR>>

Overflow Questions 6/1/06 Hello Bob and the WWMC, <James with you today.> I hope all is well and Hawaii was fascinating (jealous). <Talking for Bob, Hawaii is always fascinating, something different on every dive, correct, Bob?> <<Mmm, yes, but back in sunny southern Cal. now>> I am starting to plumb my 50 gallon sump and refugium to my 150 gallon all glass tank and looking for some expert advice. I will make this quick because I know you are all very busy. Is it possible to connect three separate hang on overflows (1) 900 gph and (2) 1400 gph to one central 3" drain pipe with vent? <Yes, a three inch drain will handle this, but why on earth do you need that much flow for a 150 gallon tank? Problem is, if the pump is not sized close to the gpm of the overflows, you will always have problems with air in the "U" tubes. So, at least a 3200 gpm pump would be needed...That's going to be an awful lot of water moving in your tank unless you are trying to establish a tsunami biotope. Ten to fifteen times the tank volume is sufficient. You would be well over 20 times. Tell the fish to hang on for dear life.> The over flows planned positions are... a 1400 gph at each end of the tank with the 900 gph in the center. Thank you again for your time, <You're welcome. James (Salty Dog)> Mark

Re: Overflow Questions 6/1/06 Hello Crew and James, <Hello Mark> Thanks for the quick response. <You're welcome.> Hopefully these answers to your questions help clear up what I am trying to achieve. The return pump will be a Mag Drive 36 external , with a 1" schedule 80 pipe (true 1" I.D.) return to a manifold system. The manifold will have 8 outlets, if my calculations are correct I have 14 feet of head loss, total loss of 4.86 psi. Taking this into account, this leaves 852 gph of return divided by the 8 outlets, which equals 106 gph at each nozzle. If you think it is necessary, I can branch off the return line and with another gate valve control the flow back into the refugium or skimmer chamber. Sump flow is as follows, skimmer, 3 baffles, refugium, 3 baffles, return. <A bit more clearer, Mark. Think you should be fine here. Do employ a gate valve at the pump to allow you to throttle down if necessary. A return line back to the pump shouldn't be necessary. If you want to double check your calculations, here is a link for you. http://www.reefcentral.com/calc/hlc2.php James (Salty Dog)> Thanks Again for your time. <You're welcome> Mark - Overflow Box and Power Failure 6/27/06 - Hi Bob/ staff, <Hi.> I have joined a forum so I have been bothering you guys less lately, but even the members of the reef tank. com can't answer this one. Here goes. Ok, I have a hang on overflow on the 29. The overflow is by ProClear and has the overflow box with slits and a u tube that carries that water to the pre filter on the back. <Very common design.> suppose this happens. The power fails for an extended period while am away. So the overflow will keep draining water into the sump until the water level drops below the slots, no biggie. But then the power comes back on and the return pump is working again. So all that water gets pumped back and it fills the overflow box slits. Will there still be a siphon or will the tank flood until the sump empties and the return pump blows out? <There should be if both ends of the U-Tube are submerged. This is something you can and should test by simply unplugging the return pump.> the second box that hangs on the outside of the tank is designed to retain water if no new water is coming in because the standpipes comes up a few inches and the u tube gets submerged in their. But I don't know because if water doesn't come into those slots in the internal box, and all the remaining water gets sucked up by the u tube, wont it suck air and have no siphon? <It doesn't start moving until water flowing into the slotted (tank-side) box.> I'm really worried so if it will loose siphon, what can I do to prepare or prevent the possible flooded floor, blown out return pump, and likely fire? <Well for starters, everything electrical in and around your tank should be plugged into a GFCI outlet. That will remediate any possible fire dangers. Otherwise, I think you should unplug your main pump and see what happens. I think you will be surprised. Over the long haul, just keep the U-Tube clean as this is the weak link in the chain.> Remember to look closely at the picture provided in the link. <Am very familiar with this design; have sold more than I care to count.> Thanks John <Cheers, J -- >

Overflow box/es...? 7/31/06 I am in the final stages of setting up a 157 gal reef tank. Besides the tank volume it will also have a 40 gal sump. I bought a Iwaki pump rated at 1100 gph. My question is how large of a overflow box should I purchase (I know a drilled tank would be best but one buys what one gets a great buy on) Should I purchase one rated at 1100 gph or one larger and then adjust it to the flow I need. Thanks Robert <I would purchase/use two such designated flow devices, if not re-consider having the tank drilled... Much to discuss... Please read here: http://wetwebmedia.com/overfloboxfaqs.htm and the linked files above where you'll lead yourself, till you feel confident re what your choices are, your best direction here. Bob Fenner>

Hang-on-tank Prefilter/Overflow boxes 11/21/06 Hello, <Hi Michael, JustinN here with you tonight.> I have a 75 gallon display tank and would like to use my 38 gallon tank as a sump/refugium beside it. I am considering the Lifereef prefilter box to move water into the sump and a mag drive pump to return it to the display tank. I want to make sure that the Lifereef is the best option to avoid floods during a siphon break. I will also use two check valves on the return line to avoid a reverse siphon. Please let me know if this is a reliable product. Thank you. Michael <Well, Michael, I can't speak specifically towards this specific product, however, with overflow boxes, its a good idea to go with 2 overflows with flow control for redundancy. Assuming the output is adequate for your envisioned setup, I would imagine this product to be sufficient. Hope this helps! -JustinN>

Siphon Overflows Hello, <<Howdy>> I had a question about possible flooding with hang on overflow boxes, since I live on the second floor of an apartment building am a little concerned. <<And rightly so...>> I have a 75 gal tank with 2 CPR CS90 overflows, a 20 gallon sump, with a MagDrive 7 pump. My question is would it be possible to use an auto top off device connected to the return pump with the sensor sitting high in the tank keeping the pump constantly running, if for some reason I had a siphon break, the sump would then fill the main tank triggering the float switch, shutting down the return pump and avoiding a flood. Would this work and if not do you have any other suggestions for me? <<In theory maybe, but float switches can fail too. Is good that you have two overflow boxes...do have a read through our FAQs re: http://www.wetwebmedia.com/ovrfloboxfaq2.htm >> Thanks a lot for your time, Chris <<Regards, EricR>> Durso Standpipe in an external (hang on) overflow box 1/31/06 Hi, <Howdy> I have a 1 1/4 DIY Durso standpipe in an hang on overflow box. I purchased the overflow box from my LFS. The box did not lose siphon in a simulated power outage before I installed the Durso, but now it does. <Yikes, or potential yikes> The water is siphoned from the inside chamber too fast and siphon breaks. <Yep> I have tried to extend the U tube way below the intake from the Durso, but to no avail. I can't even get the U tube to hold siphon with the power off. It seems there isn't proper equilibrium between the inside and outside boxes. Any advice is appreciated, Thanks! <... Well, there are plumbing arrangements that can be fashioned as a work-around repair here, but they require a bunch of space... more than you likely have. There are other solutions... that call for something other than the Durso you have situated here... and these are posted... you guessed (!) on WWM. Bob Fenner> - Setting Up a Durso Standpipe - Hello, I went yesterday and bought all the parts for the Durso standpipes. I have a 1" bulkhead and got all the parts according to the instructions. Problem, I just assumed these items would fit into my overflow, they didn't. I think I might be able to get the 1" PVC, street elbow, tee to fit inside, but the 1-1/4" will not fit for sure. <Ok.> I read on the website that using 1" PVC is not effective, my tank is roughly 60 gallons. <One inch should work... given the fact that you probably won't have nutty recirculation on a tank of this size... would certainly experiment - glue the T-fitting and street elbow together and just press fit on top of the stand pipe... see how that works for you.> Any suggestions on reducing the noise? <Give this a try first and see how things go... if your tank is still noisy, do read through the plumbing FAQs... I've posted a couple of different solutions there.> Thanks, Rajiv "Mickey" R. <Cheers, J -

Clams and Overflow box question? 2/17/06 Good morning to you- I love this site and have been using it faithfully for a year. But alas... I now need to ask a few questions. I have had a 38 gal. tank for over a year. I am now getting ready to build a 135 gal. 72L x 24W x 18H w/ a plenum and 3 in. LS, 155 lb. LR, 2000 gal. an hour filtration. I have been reading all the articles on Clams and Lighting in reference to water depth, among others. But I am not sure I can do what I am thinking (I may have missed something). I would like to know if w/ a 520w Compact light (6700K/10000k, 420/460nm) in 14 in. of water depth if a Tridacna Crocea would be happy and healthy or would I need to still have a MH? <Should work> Next... I am planning on putting the skimmer box in my tank like in Anthony's diagram. I am putting in 4 bulkheads 1.5 in. ea., the box will be 48 in.'s long centered. I want to leave the sides open for water flow from the manifold around the top. Is this enough bulkheads for the 2000 gal. rate of flow I want to get? <Should be, yes... If it were me/mine, I'd make two (the outside ones), 2" ID, put the bottoms near the same level as the 1 1/2"s> And will I get my flow rate if I use y connecters and plumb 2 an 2 together or should they be plumbed separately for better flow? <Can be linked together... need (likely) to be aspirated to speed flow, reduce noise and "bubbliness"> Thank You for your time-Deanna- <And you for your sharing. Bob Fenner>

Keeping Peppermint shrimp out of overflow and to sump - 02/16/2006 Good day, Cant get enough of this website and I am inspired by all of your generosity with your time and expertise. Outstanding! I read the peppermint pages on WetWebMedia and did not see this question. Background: When adding peppermint shrimp to the display, they seem to find there way to the overflow box and go down the standpipe into the sump. I want to keep them in the display to combat Aiptasia (until I get my excess nutrients under control-working on it). On another site, I asked and someone suggested counted cross-stitch plastic sheets from craft store cut to size to keep them from the overflow. <One choice. Some sort of chemically inert screening> Well, it works great at keeping the peppermints out of the overflow and in the display, but now an oil slick is on top of the water of the display as the counted cross-stitch material is apparently keeping the oily stuff from getting into the overflow and down to the sump to skim, probably due to surface tension. <Ah, yes... perhaps a larger mesh material> I live life dangerously only have one overflow on this display by the way. <Heeee!> So, the question is: is there a better way to keep the peppermints in a display and out of the overflow without obstructing the surface oily from draining into the overflow? Sean Missey <The screening/sieving is the easiest approach here. Try something of a bigger "draw". Bob Fenner>

Plumbing an Overflow in an Established Aquarium - 03/09/2006 Hello WWM crew, <Hey Joe...(sorry, one of my favorite songs:)> I have had my aquarium for about a year. It is a 55 gallon FOWLR. I want to make the jump to making it a reef aquarium. <And into the rabbit hole we go.> For the last 8 months I have used a DIY Ecosystem style sump with miracle mud and Caulerpa algae. When I installed the sump I made a DIY overflow box. So far I have been lucky with the overflow box and haven't had any breakdowns. <We're safe...but for how long? (The Kids in the Hall)> In fact, the syphon hasn't been broken once since I installed it. But more and more I want to get away from it. I want to be able to cover the tank better because I have lost a couple fish that jumped out. Also I am constantly nervous that it will malfunction. <Rightly so.> Every once in a while I hear the noise from my bedroom and I can't sleep for worrying (this happens rarely but when it does it is quite nerve racking). I was wondering if it would be too difficult to have the tank drilled now, what it would entail, and the impact it would have on my livestock. <And back to the song "Hey Joe, where you gonna run to now? Where you gonna go?" Fitting eh? Drilling with all intact is not going to work. You would have to break it all down for this. My suggestion? If you can't drill it, don't sump it. You don't have to use a sump. Many hang on refugium type additions that can serve your desires here.> Thank You, Joe Lace <You're welcome. Sorry for my horrid singing (and I was). - Josh> Equipment/Overflows - 03/25/2006 Hey, <Hello> How are you doing? Anyway, I have a 55 gallon tank and I want to build a sump so I bought this over flow box https://www82.safesecureweb.com/webaquatics/Merchant2/merchant.mvc?Screen=PROD&Product_Code=ACO75&Category_Code=WDF (if it doesn't appear it's at www.webaquatics.com in the filters, wet/dry filters then titled "Overflow Box for 75/125 Filter (Pro Clear)"). I was thinking of what pump I should get for this overflow, maybe a Mag 5? or a Rio 12HF? and if those two aren't the way to go then what pump do you suggest? Thanks for your time. <I'd ask that question to Web Aquatics or Pro Clear. There is not enough info present in the ad to suggest a pump size. James (Salty Dog)> Akbar

Use of external overflows Hello: First let me compliment you on your website, it is a fantastic source of information. I have a question regarding the use of external overflow boxes equipped with J tubes. I have checked over your website and keep hearing about potentially disastrous consequences of using such devices - flooding and even fires! Provided your sump can handle the amount of water that flows down from the tank should the pump fail (won't this happen anyway when the pump is turned off for water changes etc.) and the tank can handle the amount of water in the sump should the siphon break in the J tube - isn't the worst that can happen is that the sump runs dry and your pump burns out? What about fires? Is this potentially caused by the pump burning out or by some kind of flooding situation? <Pumps can burn out... almost never with "catching fire"> I would appreciate any clarification you can provide. Steve McMullen <Can indeed be a source of disaster... if the water runs on to electrical extension devices that aren't mounted up off the floor... might indeed cause fire, electrocution. Bob Fenner>

- Plumbing/Overflow Questions - Hey guys, <Hi.> I've been using your site since I got into the hobby a few months ago! I'm new to the hobby and I've been reading as much as I can before attempting anything new on my tank. I'm in the process of building my sump/refugium and I desperately need some info. Here are my specs; 1. 155 gal glass tank, not predrilled for overflow... tank already filled with live rock/powerheads 2. Sump 36X18X20 under the main tank not yet working 3. I bought a Mag 24 and a Aqua C EV 180 protein skimmer 4. head pressure about four feet not including valves/bends... because I haven't decided on the design yet. Here are my questions; 1. Looking at CPR external overflows... looks like I'm going for two overflows. I've been looking at the 1400GPH and the 1600GPH. Considering that I will have less flow ( about 1300-1400) with my Mag pump, with the head pressure... which overflow box would you recommend? <Larger... would give you a margin of safety should one of the two stop working.> I've heard that some say to go larger while others say to try to match my output from the pump, I.e. 1400GPH 2. The skimmer water level needs to be 8 inches or lower, if that's the case will a 12 inch baffles be ok or a 10 inch between the skimmer compartment and the refugium? I've heard typically the baffles height should be 10 inches. <You could always put the skimmer on a riser...> 3. I've calculated that for the 144GPH overflows, I'll need a drain pipe diameter of 155 inches. If that's the case , the drain pipe for the pump should be less, right? What diameter piping would you recommend for the return? <Matched to the output side of your pump, which I think is 3/4" - if it isn't 3/4" - match the sizes.> Thanks a bunch guys, you've been a lot of help. Nilesh <Cheers, J -- >

Overflows Hello WWM crew, Thanks for all your help in the past.... <You're welcome> Well I'm in the process of setting up my sump for my 155 gal reef tank. The tank does not have a built in overflow system. As of now, I have the tank set up with live rock, a clown fish and the tank has been cycling through the ALGAE phases. I bought a 56 gal (36X18X20) tank to use as a sump. I've also purchased an Aqua C EV180 skimmer, and a Mag 24 return pump ( 4 feet head pressure). I'm hoping you guys can help me out, I'm looking to purchase 2 CPR overflow boxes, either 1400GPH or 1600GPH. With my head pressure my pump will dish out about 1500-1600 GPH. Should I go for the larger overflow or the smaller one? I heard that the larger the overflow box, the less noise, is this true? <If you get an overflow larger than what your pumps needs are, then they are noisier since the water is going out as fast as it comes in...lots of gurgling noise. Size the box to the pump keeping in mind the length of the return tubing so you can calculate actual water output. Every foot of return line will reduce the flow some.> Are these external boxes prone to failure cause of siphon break? <Occasionally you may get some air trapped in the upper part of the siphon, but the closer it is sized to the pump the minimal this will be.> Also, I calculated the pipe drain diameter should be 1.5 inch and the return should be 1 inch, any thoughts? <Whatever size the return is on the pump should be the size you use. Anything larger doesn't help unless the pump is going to be some distance from the tank.> Any comments would be appreciated. <I have one comment. Please capitalize all the "i's". It helps cut down our (Marina's) editing time as these queries eventually end up as FAQ's. James (Salty Dog)> <Thank you!>

Hang on Overflow questions 4/15/05 I just purchased a gravity fed overflow box. What are the chances that I will overflow my aquarium or refugium? <With regular maintenance, the risk is small. The fist test is to turn off your return pump and see how full your sump/refugium gets. While the pump is off, fill the sump/refugium to within about two inches of the top (if it isn't already). When you turn the pumps back on and the level in the sump has reached a steady state, mark this water level as your maximum. To prevent loss of siphon and overflowing of the display, be sure that your overflow is properly rated for the amount of flow. An oversized overflow (or too large or too many "J" tubes) results in slow flow that allows bubbles to accumulate, eventually breaking the siphon. Use plastic screen or "egg crate" to prevent snails and other animals from entering and clogging the overflow. Regularly clean all of the parts of the overflow to prevent algae growth from impeding flow. Siphon overflows are never 100% safe, but faithfully following these suggestions will make it as safe as it can possibly be.> Also, could I paint the internal box to match my background, if yes what type of paint? Thanks. Eric <I wouldn't suggest it. Many paints can harm acrylic, and would be likely to come off or leach chemicals into the water. A reasonable compromise is to find some plastic in an aesthetically pleasing color and cover the overflow parts with it. Silicone adheres poorly to plastics, but is acrylic safe and satisfactory for this purely cosmetic application. Best Regards. AdamC.>

Quick Question on overflow systems I was reading the section about overflows. I, like many, have a tank that I can't get drilled. I was leery about siphons and you guys have convinced me that I'm right to be weary. I run a H.O.T. power filter, It seems to lose suction and start back up with power turned on and off. would tapping into the bottom of the power filters sump be a way to go? <How would you re-start the siphon if/when the water drained down past this?> then all that would drain out in a failure would be what was in the power filter's sump. might not have all the flow I want but I already using hidden power heads for that anyway. Thanks in advance. <Could work to return the water... once. Then your filter would run dry... Bob Fenner>

Re: Quick Question on overflow systems Okay I get what your talking about now. You're right the pump will lose the water it needs to prime if there is a power failure (for the record I would use a check valve for the return). <... my friend... a check valve will do you no good here> Therefore I would need to use a stand pipe that would be just below the power filters overflow to the tank. That would keep the water in to keep the pump primed but would allow me to flow to the sump without fear of a siphon flood problem. Thanks for your help. By the way, I picked up a copy of the May 2005 Tropical Fish hobbyist And I see an interesting story about summer homes for fish, very cool, I enjoyed reading it. Well, my quick question has become 3 emails. thank you for your time. I appreciate your help. Jay R. <Do try making a sketch of your desired plumbing layout... and share with like-minded aquarists... You'll get it right am sure. Bob Fenner>

Re: Quick Question on overflow systems I appreciate your quick response, but I don't think you got what I was trying to explain. So let me see if I can explain it better. I mean to use the hang on the tank power filter (a Whisper 60 by the way) as a pump to pull water from the tank. Leave the filter intact so that the pump on the filter could pump the water. There would be no siphon at all. put a hole in the bottom of the filter sump and as water is pumped in, it would drain to the wet dry below. I would probably need a valve to slow the flow down to not lose prime on the filters pump and if the valve got clogged the water would flow back into the tank as if it were un altered. <... we're back to the original query/problem... what will happen if/when the power fails, or a pump goes... like the pump that will return the water from the sump (being fed by the hole in your outside power filter hole in the box?)... Can you visualize this? Am I missing something in this discussion? Perhaps try rigging this up, turn the power off for an hour and see what happens... the water will drain from the power filter above to the sump below, breaking the siphon/connection twixt the main tank and power filter... and if/when power resumes, the sump will pump itself dry. Please read over an article I've penned on marine plumbing: http://www.wetwebmedia.com/marine/setup/index.htm and the many plumbing FAQs files linked here. Bob Fenner>

Pump Selection And Overflow Box Modification - 06/28/05 Hello crew. <<Evening>> I am having a tougher time than I thought choosing a return pump for my 135G FOWLR. <<Let's see if I can help.>> I am gonna run a Marineland S.O.S. rated @600gph max. <<I always take manufacturer rated flows with a LARGE grain of salt...would suggest two of these if possible for redundancy/safety sake.>> Some pumps that I am interested in either come up a little short, or are too much flow. I am thinking it would be wise to go with the larger pump, and dialing it back if needed with a ball valve on the output. <<Using a pump rated at "less" flow than the overflow is not a bad thing (I hope this is not your only source of flow in this tank.)...and may just be a smart thing based on my earlier comment. It is also possible to "throttle back" a larger pump as you stated, but unless you will need the power/flow later on, why waste the money on the purchase/power consumption?>> Now, there seems to be two classes on most external pumps. Pressure pumps, and circulation pumps. <Yes>> Can either one of these be dialed back with a valve? <<They can be, yes. Though some direct-drive pressure pumps may suffer in the long-term from "excessive" back pressure.>> Can a pressure pump be used for wet/dry return? <<Sure, but I would suggest a circulation pump for this purpose for reasons of cost/power consumption/noise. Iwaki would get my first vote, GRI a strong second.>> Can I dial back a submersible pump with valve? <<Is what I do. Mag-drive pumps take this very well and provide good value/service in this role in my opinion.>> I suppose all it would do is make the pump think it is pushing at a higher head and not hurt it. <<Some pumps handle this better than others.>> Secondly, about my S.O.S. I have two of these at my disposal, and am thinking of modifying one. I do not know how familiar you are with these, but let me explain briefly. <<Have seen these.>> It does not have typical u-tubes. More like a flattened u-tube about 4 inches wide. Then it has two holes to go down to the sump. One is the main flow, the other is just in case the other fails. <<Mmm, not really. The second outlet is not for redundancy...you need both of the outlets to even get close to the "rated" flow.>> Here is what I am thinking. Replace the flat u-tube with two typical 1 1/8"OD u-tubes, and use both drain holes. Maybe then I could get more out of it. Something like 800-1000gph? <<Seriously doubt it...these devices are limited/risky by their design/function...it won't matter how "big" your u-tubes are, you're still limited by the drain size...just as in a gravity overflow. I wouldn't bother modifying the overflow. I would instead use two overflows and then shoot for the 800 gph between the two...much more peace of mind. Sooner or later a siphon overflow WILL fail.>> Do you have any comments on this, or things I should be aware of? <<Yep...as stated <G>.>> Thank you guys. <<Regards, Eric R.>> Almost There! Question on Overflow box Gentlemen Greetings, <Adlai> I was finally about to setup my tank after curing my LR for 8 weeks and doing my due diligence i.e. reading FAQs, daily researching etc when I realized that my flow going into my sump might be less than my return. Could you please tell me how to (or where to go to ) calculate the flow of hang on profiler/overflow box with a U tube (drilling my tank unfortunately is not an option at this time)? The dimensions of the pre-filter and my overflow box are respectively 2.75D x 6L x 6W inch and 10.5L x 4.5D x 6W inches and uses a 1 inch bulkhead. <Mmm, am hesitant to offer other than a guesstimate here. Know that there are other factors that do determine actual flow rates... induced drag, horizontal runs... Roughly speaking, you can expect a good 300 gallons through this line... In actual practice, I would and strongly encourage you to try it out... measure the flow with a time piece with a second hand... and a measured container...> Also CPR has a hang on overflow box with no U Tube which it clams is better because it provides a continuous siphon do you recommend this over the U tubes?. <Yes... this is a far superior design> My eventual setup is a 55 gallon hexagon flat back with a sump (a converted wet dry with Live Rock). The sump has a EuroReef skimmer CS6-1 w/pump, a small MiniJet 606 pump (this powers my 10 gallon refugium which returns its flow back into the sump), a Eheim 1000 compact pump (this powers my SCWD for extra circulation back into my tank) and I have a Rena Filstar XP2 for chemical filtration and additional circulation. My return pump, an Eheim 1060 is attached to my sump via a bulkhead. This will be for a FOWLR setup On last question, the LR which has been curing in my Rubbermaid container is "turning brown" and the container has some brown slime too. Is this OK?. <Yes... to be expected... swoosh the rock, water around to remove when doing water changes, moving the rock> I assume it is algae. Since I will be placing it into my main tank do I need to do anything? <Not to worry. Is mainly algae... not a problem. Bob Fenner> Once again, my future fish population and I thank you.

Overflow boxes (sent by FAMA) Hi, I am a subscriber to your Mag and it's the best! I have a question for you. A friend of mine gave me his 150 Gallon All-Glass Aquarium. I want to install overflow boxes. All-Glass does not supply them for this size. Do you know of anyone that makes them for a retro fit application like mine? <The best site, line to start with are those by CPR, Creative Plastic Research. Their link: http://www.cprusa.com/ Other manufacturer's can be found on the Links Pages on our principal site: www.WetWebMedia.com Bob Fenner> Thanks for your time! Tom Tompkins

U-tube overflow modification Hello, I use an overflow box with a u-tube. Every week it seems that I must re-siphon the u-tube, otherwise air enters the tube and tends to decrease water movement to the sump and increase the water inside the overflow box, causing less flow and less water movement. Is there any fix to prevent this? Thanks, Rob <the best solution is to not use an overflow at all... they hold you hostage in fear of the inevitable overflow from a siphon break... even the best designed ones can fail. Do have the tank drilled for a gravity overflow when you can. In the meantime, there are many DIY solutions on the net to help with this... simply do a keyword search with the pertinent terms. Also look on the DIY link at www.ozreef.org... I think a saw plans there for a better mousetrap. Essentially, what you need to do is drill a small hole at the top of the tube, glue a rigid airline stem in place and hook it up with the Venturi of a nearby powerhead. This Venturi will constantly siphon air bubbles that collect (with water) and prevent the siphon from breaking. Best regards, Anthony> Rob Cook

DIY Overflow Hi, <<Hello,>> I've been reading your FAQs since I started my first marine aquarium this year. It's just a 29 gallon tank with a couple fish, some crabs, and just recently 2 anemones. I figure that this is my learning tank before moving on to something larger. I have a Prizm skimmer, Penguin Bio Wheel power filter with a Fluval surface skimmer attached, and a Zoo Med powerhead behind the rocks for extra circulation. Anyway... I just added a new 200 watt Ebo Jager heater (also behind the rocks), and a CustomSeaLife SmartLite to the mix, and I realized that space is getting tight... Because of the light I can't reach the skimmer to adjust the flow without removing the light, and I don't like the heater laying across the bottom of the tank. I realized that I have several 10 gallon tanks collecting dust in the garage, so my natural thought was that it's time to add a sump to my learning experience. That would allow me to move all the mechanical devices below the tank except for the power head (which is the only piece I've really been able to conceal well anyway). I've been looking at overflow boxes, and the ones that are available are way too big for this little tank, and too expensive to boot, since when I do get a larger tank it will be drilled for a sump anyway, so why blow $70 on something that I won't be able to use on a new tank down the road. After looking through the DIY plans online I just had an interesting idea about making an overflow box, and am seeking an opinion as to whether it would be a good idea. I read one of the plans where a person used an old power filter as the outside box. all the parts were gutted, and the hole where the pump goes was used to place the bulkhead for the plumbing. My thought was... Why gut the filter??? Add the overflow box onto the front leaving the filter tube in place so that it's inside the box (cut down if too long), and why remove a perfectly good pump??? Just add a piece of acrylic to divide the media chamber drilling the opposite side from the intake for the bulkhead. Now you have an overflow with a priming pump built in... Just plug it in until the siphon starts, and then unplug... If the siphon breaks you can just plug it in to re-prime it. Any problem with this that I'm missing? <<Only if you forget to unplug the pump... the pump mechanics would also reduce flow when the pump is shut off. Although this is a neat idea, it's probably not optimal.>> Aside from the fact that it would be limited by the diameter of the intake tube, but for a small tank it could be just the thing, and who doesn't have an old power filter or two laying around wasting space? <<True.>> Thanks, Jeff Cowles <<Cheers, J -- >>

Overflow <<Greetings, JasonC here...>> I have a 20 hex I am going to use for a refugium and you said "PLEASE don't use a siphon overflow, drill the tank." What is your aversion to siphon overflows? <<They clog very often and need regular cleaning. The clogging can/will cause the tank to overflow and perhaps your return pump to run dry.>> I am looking for some advice as to where to drill the holes into the back of the tank to install the overflows? My guess is as close to the top frame as possible leaving enough clearance so the bulkhead fitting will clear the frame, is that correct? <<Yes, would be my choice.>> My LFS (189 miles away) has only drilled the bottom of tanks and did not have any ideas where the holes should be drilled in the back of the tanks. I am very limited on the size of the hole I can have drilled. My community is very small and only on glass shop drills glass. Fortunately, they can drill 1 ½" holes. I know this probably seems like a stupid question, but I have already made enough mistakes, I don't want to make another by ruining a perfectly good tank <<Not a stupid question at all. Cheers, J -- >>

Overflow to sump & gph to and fro Hello All/Some/One: I read in section http://www.wetwebmedia.com/pbfaq6mar.htm where Mr. Pro (stage name?) wrote: "I would not take a siphon overflow for free and I would never even think about using one in my house". If you are not Mr. Pro, do you agree? Is the actual problem of breaking siphon that the sump's contents will then be emptied and cause the display tank to overflow? <Nope, the opposite> If so, what is a person to do with a 55gal all-glass that is already set up, but is now looking into sumps/refugiums? At this time, I am not ready/willing to break it down, bring it to a professional, have holes drilled and an overflow put in (which I also read that they may not even drill/warranty my tempered-glass bottom!). Can a safety switch be purchased (or created) that when the water level reaches critical in the display, the pump will shut off? Please help with some solution other than "get yourself a tank with a built in overflow" wink!). Also, please clear this up for me; if I have 1000gph overflow to sump, and 600gph return pump, does the overflow part slow down? <Yes, the overflow can only remove as much water as is being returned to the tank.> How about the opposite: 600gph overflow and 1000gph pump? <This would be a waste of pump, the overflow would be too restricting.> Or does neither work and they need to be equal (can't be, right?)? I have read so many FAQ's that I think I am confused again. Regards, Rich. <Hey Rich, drilled overflows are always going to be safer than siphon overflows. The problem with siphon overflows is the potential for problem. In theory they work well, say for example your power goes out and your pump stops, then the tank drains down to the level of the overflow box that is positioned on the inside of the tank. But what if the suction cups that hold it to the glass are old and no longer fit tight, then water will suck through these holes and overflow your sump. Or maybe the return from the pump starts siphoning water back into the sump in the even of a power failure, another chance for your sump to overflow. Another problem is air gathering in the top of the siphon tube and breaking the siphon, then the pump drains the sump and burns up. Than being said, make sure that the suction cups fit tight, drill a small hole just below the water line on the return to the tank to break the siphon in case of a power failure. You can also drill and attach some airline tubing to the top of the siphon tube and attach the other end to the Venturi portion of a power head, so if air does gather it will be sucked out. Hope this helps. -Gage>

Pre filter/skimmer J-tubes losing prime [AKA... you can't polish a turd] Jason C, could you please forward this email to a few of the other members of the organization? Perhaps they may have an alternative method to fix this problem that you may not be aware of. I mean, it IS possible. <at your request, your message has been forwarded to me, bud. Anthony Calfo in your service> I was thinking that perhaps extending the J-tubes by about an inch or so into the intake compartment may help keep them deeper, so that when the power fails and the little intake drains to a certain point, the J-tubes would still be below the surface of the water. <J-tubes are inherently flawed and inferior devices. I'm not exaggerating when I say that I would not sleep in a house with this application. In ten years I have heard of numerous failures by siphon overflows, and two of them caused house fires. Better designs may carry you a year or two... even three before a failure. But then again... maybe not. There are modifications of the design that include drilling and tapping the top of the tube with a check valve and airline. This is then connected to the venturi of a powerhead to help prevent the siphon from breaking. It is helpful but hokey. It relies on the power head restarting after a power outage, and some do not. The venturis clog fairly quickly and often. And even when the best modifications and performance of a siphon overflow are in place, it can be wrecked in an instant by a low running sump that throws bubbles into the main display or even the literal addition of an airstone or PH venturi in the tank. Any bubbles that reach the surface can be overflow and overwhelm the j-tube... breaking siphon. The moral of the story... "You can't polish a turd". I would rather not have a sump or trickle filter than be forced to live with a j-tube. Sorry, bud... it is what it is> It's things like that that I'd like confirmation on. <understood and agreed> I'm just guessing that it might work. <I'm sure it will fail in time. I have yet to see a modification for three years without a catastrophic event. Most don't even make it to one. Case in point, how many overflows have you had already?> Please don't reply "Well try it and see". <no worries here... I'm suggesting you drill the tank or drill the sump/trickle and treat it like an upstream refugium (mount it above the display and pump up to it, letting water overflow down and the display becomes the sump> I just wanted a few more opinions from the staff on your end. Maybe they've encountered similar problems with the J-tube <yep... about 15 years worth including an investment into a commercial j-tube set-up for about 1000 gallons worth of breeder tanks> arrangement and KNOW what seems to remedy the situation. <yep... remove it ASAP my friend> Thank you for all of your assistance. Steve <best regards... wish I could have borne better news for you. You have your work cut out for you, bud. Find whoever suggested this j-tube to you by the way and kick them in the jimmy. Drilled overflows have been the mainstay for a decade. Anthony>

-CPR overflows- Hello WWM, I was read the FAQs today & saw this statement from Kevin, concerning CPR overflows-->"<I'm a J tube user for life (if drilling isn't an option!), the CPR overflows are horrid, and I'm not sure about the Tidepool ones as I haven't used them> <-- What makes the CPR overflows "horrid"? Just curious, I was thinking about getting the 1400gph CPR overflow myself! <Heh, I knew I'd have to explain sooner or later. I've used the CS90 and CS102 (the 1400gph one you're talking about) both on my personal tank and at the shop. My main reason for disliking them is that a small pump w/ venturi kit is required in many cases to suck the accumulating air out of the top of the siphon "chamber". This pump then spits the bubbles into your main tank, that is, if it keeps sucking the air out because, w/out frequent cleaning, the nipple provided to suck the air out get's clogged. When this happens the chamber will eventually fill with air; breaking the siphon. Although I have had bad experiences with them, not all have, and some actually swear by them. A quick ReefCentral or reefs.org search will get you several more opinions on the subject. Personally, I find that the additional cost and potential problems make a J tube style overflow choice a no-brainer. If you wanted to try a CS series overflow, make sure you match the flow closely, and be willing to deal with the unique issues surrounding it. Hope this helps! -Kevin> Thanks, as always, Scott in Denver

Overflow Question Hey! How is everybody? <Beautiful day in San Francisco. Ryan Bowen with you today> Thanks again for such a great site! Got a question. I have an established 40 gallon tall and I want to add a sump but it just isn't possible for me drill holes for an overflow. <Hmm...Most overflows require no drilling at all> I'm not sure how to get the water movement correct. <Choose an overflow with about a 400gph rate. Since you're not going the drilling route, you will need a submersible pump, and don't skimp. The cheaper ones add a lot of heat to the water.> I have a ten gallon laying around that I was planning on using for the sump. <Go to PetCo, get a super-cheap 20-30 gallon instead. The extra water volume is the true reason for all this labor- 10 gallons is barely worth the effort.> I was thinking about using 2 of the same pumps (quiet ones, 300gph) to move the water to the sump and back up, into a SCWD wave maker, then into the display tank. <Hmm...I would use a CPR Overflow or a Tunze outlet. Look up some DIY Sump designs here: http://ozreef.org/ And then pump it back up with an adequate pump.> I don't about all the water pressure, gravity, calculations and stuff. <Trial and error can be pricey, so you may want to read the Circulation FAQs> The top of the tank is about 4ft off the ground. What can I do to make this work without drilling? <See above> My main focus it get everything I can out of the display and off the back of the tank. <Great> The health of the tank is good and I think a sump could make it much better. <Can't improve perfect health!> I cant afford a bigger tank and I want my 40. Any advice would very much appreciated. <Surely! Good luck, Ryan> -nick

Siphon box prefilter 1/15/03 Hi Crew! Easy question today. As I do not have a drilled tank, I am forced to use a hang on siphon box. I seem to remember reading that the foam filter should not be used as it will go biologic (sp?) and then become a source of nitrite/nitrates in the sump. Is this correct? If so , should the foam filter be used? or just go without? My sump is really just a refuge with live rock rubble for growing critters. Thanks as always. <Some nitrate will be produced in the sponge filter, but I doubt it would be enough to be of concern. Unless you need to protect the drain from snails or other animals/objects entering and clogging it, there is no good reason to have it. Bottom line... I would base the decision on flood risk, not nitrates. HTH. Adam>

Re: siphon box prefilter 1/16/03 Adam, I'm sorry to bother you again but I did not post my last question very well. I am so stressed out about this, that I can't write clearly. Maybe I need a hobby? I know! I'll get a aquarium! <No bother at all! And by the way... I tried that I need a hobby, how about an aquarium thing with my wife and she didn't buy it for a second!> With the overflow drain pipe going into the sump, should it be above the water level in the sump or should it be below?? Thanks <Sorry for passing over this part of your question. IMO it really doesn't matter. I prefer to put under water because I found it to be quieter and makes less salt creep. HTH. Adam>

Re: siphon box prefilter// follow-up 1/15/04 Adam, Thanks for the fast reply. I was referring to the big round filter in the drain box on the back of the tank, not the skimmer box with "teeth" on the inside. Would you still not use the cylinder shape foam filter? <Hmmm... I am pretty sure that is what I was thinking. Snails can be quite feisty and climb over into the "outside" box of an overflow assembly.> I also have a question on the drain line going into the sump/fuge. It is a 1" PVC pipe going straight down. I have checked the FAQ and some say the pipe should be above the water line, some say it's OK for it to be below? I am trying to make it as quiet as I can, but it still makes a loud flushing noise. Is this just the "nature" of these boxes? Are they all noisy? Thanks again! <There are a couple of ways to quiet this down. One is to build a "Durso" stand pipe in the outside box of your overflow. If you do a search on the internet for "Durso stand pipe" you should find a diagram. You can also cover the top of the overflow box to muffle the sound. Best regards, Adam>

-Who's rating these overflow boxes?!- Hi Guys! This is the first time I'm writing (most of my questions have been answered by searching and reading the FAQ's). <As most should! A big pat on the back for excellent self research! We're glad you've found it useful.> I want to say first, thank you for the awesome site. It has helped me out enormously! My question has to do with an overflow box that I purchased a while back. Basically the overflow box contains a prefilter box that sits in the display, two J-tubes that siphon the water out of the prefilter box and a holding container in the back with two 1" bulkheads for draining. It supposedly does 1200 gal/hr. <1" U/J tubes can handle around 600 each, so that sounds good.> In a nut shell my circulation goes like this: Water siphons out of my display via my overflow box which then is transported to my sump via two 1" flex tubes that dump the water into the first compartment of my sump. A Mag7 pump (external) pulls water out of the first compartment and pushes it into the ETSS Reef Devil Deluxe skimmer (external) which empties the newly skimmed water back into the first compartment. The water goes under the first baffle and over the second to enter the refugium (sump dimensions are 24W X 18D X 16H, the refugium is 15W X 18D X 16H). It then overflows into the last compartment where it is sucked up by the Little Giant 3MDQX-SC and is transported through 1" PVC piping and a 1' black tube back into the display having to first pass through a ball valve, check valve, and two 90 degree bends. The Little Giant pump sits about 4 ft. from the top of the tank. With two 90 degree bends, all the valves and tubing, plus the 4 ft. of head pressure my pump is pumping at most 875 gal/hr (rated 1,000 gal/hr @ 3 ft. head)! And that's looking at it from an optimistic view point. Currently, if I don't close the ball valve on the return about an 1/8 of a turn the pump will pull all the water out of the third compartment faster than the overflow can put the water there! <Hmmm...> I'm wondering did I purchase a junk overflow box (it is a non-named brand, purchased from a plastics company) or is it my setup that is slowing the water down too much? <The overflow box should be fine as long as the u-tubes are the standard 1" diameter ones.> Should I purchase an overflow box with a little more capacity to keep up with my pump? Everything works right now but I'd like to use the full potential of my pump. If there are any suggestions you could give me I'd really appreciate it. <Suggestions: Assure that there are no kinks or needless 90's in the tubing running from the overflow box to the sump. Make sure nothing is blocking the 1" drains in the overflow like clogged sponges. Check to make sure that the problem isn't simply a case of not enough water in the sump by opening the valve on the pump, and adding more saltwater to keep the chamber full. You'll want to stop this madness if the tank looks like it will overflow and take all that water back out. Heck, if it doesn't work you've just done somewhat of a water change! Basically, there's no reason that you can't run your pump full throttle on this setup. If the water is draining unrestricted, then maybe the u-tubes are too small or clogged. Try a few more things before giving up on your overflow. I hope this helps, I'm sorry I don't have a straight answer for ya! -Kevin>Right now I'm looking into getting a new overflow box from a different and notable company that is rated at 1400 gal/hr but wanted to know if it will even help. Thank you very much for your time. Chris

New tank isn't drilled (but overflow required!) Hello Bob, would like to know which overflow would be ok / compatible with the jewel Trigon 350ltr,and return pump required (Eheim 1260/ ocean runner 3500 or what do you advise! <I am much more "positive" re the use of such add-on overflow "boxes" than many of my cohorts here at WWM... for a system this size, for safety's sake, I would utilize two such devices... either tying in their discharges to your sump with a tee or allowing each to overflow separately> Sump size is going to be roughly 27x15x18 with live rock, Caulerpa and then return probably housing carbon/ heater. Rowaphos I would put under direct flow from overflow in a basket or something. Would you suggest any material different from above in relation to sump, your expert advice would be greatly appreciated Thank you ,I Smith, Preston, Lancs, UK. <All sounds about right. Bob Fenner>

Friends Don't Let Friends Use Siphon Overflows 9/7/04 Hey guys, <howdy> So I have the old Amiracle hang on overflow, and was running a 1 1/8" inside diameter u shaped tube. I took out the u shaped tube and constructed a standpipe of 1 1/2". <hmm... I see the illustration mentioned below. Your "standpipe" really isn't one... it's still a siphon overflow. A standpipe is an open-mouthed gravity overflow "drain" by some definition of the word> Click here and look at the first picture that comes up as you scroll down the webpage to see a picture of what it looks like... http://aquaticpredators.com/forums/index.php?showtopic=13 It worked well and was able to draw out more water from the inside skimmer box (inner box) to the outer box more than before. <a larger bore siphon, yes> After I saw the result of this (more water being drawn out), I decided I needed more flow rate coming from my return pump. I basically went from a 3/4" return line to a 1" return line and took out all of the 90 degree elbows that I had at the top of the return line and put 45 degree elbows instead. This in turn gave it less back pressure, allowing the pump to push more water out. However, after doing this with the return line, my inside skimmer box (inner box) couldn't take this much flow rate. What happens is the inside skimmer box gets filled up with water and overflows back into the aquarium and unless I turn the return pump off, the aquarium overflows. My questions are the following: <the pump simply needs a gate valve off the top of it for fine tuning the outflow> What can I do to make my overflow be able to take more flow rate? <I do not trust or recommend siphon overflows of any kind. They are patently unreliable and a danger IMO (flooding and worse)> Shall I need a bigger inside skimmer box (inner box) to take more water in? <my very strong advice is to have the tank drilled with enough holes for a proper flow> Shall I need to make the standpipe bigger, from a 1 1/2" to 2"? <you cant polish a turd <G>> Or did I just miss something in the process, or leave something out? I can't figure it out. Just to let you know, my bulkhead on the outer box of the overflow is a 1 1/2". So the problem isn't on the outer box of the overflow, it's on the inner box of the overflow (or skimmer box); it just can't handle all the water flow from the mag-drive 12 that I have as a return pump. Any help would be greatly appreciated. Thanks, Hamilton <do drill my friend... you will not regret it. Just be sure to drill enough/large holes. Anthony>

Making a homemade overflow Dear Adam, << Hey Narayan. >> My Eheim 2227 wet/dry failed today. A few days ago it was unable to pump water up against the head pressure and I had to restrict the inflow just so that the pump can keep up. Today it started to leak out of a seal.... Fortunately it was devoid of media and merely added to my water volume and flow -It did give me some surge type flow though! I'd like to replace it with a 20L refugium under the tank. << I hope you mean 20 gal, because 20L is pretty small. >> My plan is to have a small initial chamber to add a media bag with carbon and PolyFilter , followed by most of the tank that will be 4" DSB, macro algae, 'pods, all lit up 24hrs or reverse -not sure yet... any opinions? << I'd go reverse lighting. Sounds good to me. >> And a final chamber with the pump that will be sized for about 100gph flow. << That is very little flow. I'd go around 800 gph. >> The display is a 72G with 4.5" DSB and 75-80lb live rock. Currently my circulation is just (2) Seio 620 powerheads and a Remora pro with Mag3 pump. Total flow 1700 gph in a 72G - probably more like 1200 gph and 60G of water... My tank is not pre-drilled. I am torn between a CPR overflow with the Aqualifter pump or a home-made over flow that will have (4) 1" U-tubes, each one quite capable of handling the 100gph flow should the other 3 lose siphon. I'm not sure I want to rely on the Aqualifter not failing -after all, I just had a $175 Eheim filter fail me is a little over 14 months! Which one would you recommend? << If you can afford it, I'd go with the CPR overflow. If you want to save some money there are lots of people out there making their own overflows. Before making one I'd get some friends to come look at it with you. >> Thank You, Narayan << Blundell >>

Hang On Overflow Box When you use a hang-on type overflow box with a wet/dry sump filter, does that produce any noise problem?<There will be some> I've read that the tanks that have the built-in overflow are noisy? I've searched your site but can't find the answer. Please help! <I've had several tanks with built-in overflows and found none that were distracting to me, unless this tank is going into your bedroom, you'll be better off with the built-in overflow as they have fewer problems than the hang-ons. James (Salty Dog)> Mitch

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