Tank Sump Flow Balance Problem <?> 8/5/05
We're having a flow balance problem we need help with.  Setup is basically a 125GL acrylic display tank with a 60GL sump/refugium, plumbed with two CPR CS10 (1400 GPH) overflows on a 1-1/2" line to the sump (ball valve in line to control flow to the sump),
<No need....>
and a Supreme
MD36 Mag Drive Pump (3600 GPH @0'head) return, split into three 1" return zones, off of a 1-1/2" PVC manifold.
Zone 1) 3/4" manifold to five LocLine valves around the top of the tank, controlled by a 1" valve,
Zone 2) 3/4" manifold to two LocLine valves at each end of the tank, bottom and back, and to a SCWD, center of the tank, on a 1" valve
Zone 3) a 1" bypass/return from the sump pump, back to the sump (to balance flow) on a 1" valve.
The sump is divided into three areas, first, 7" wide, holds a Turboflotor 1000 Multi skimmer, three baffles (over, under, over), an open area for a future refugium, baffle, and 6" pump area.
<Okay>
Now, a balanced flow between the tank and the sump can only be reached by shutting off the zone 3 bypass valve, and low tank zone 2 valve, and closing the upper tank zone 1 valve to one quarter open. The flow from the upper zone 1 (five outlets) is only moderate (not even as much as a power head).  It seems that the flow from the CPR boxes (straight drop, one 90 elbow, no restrictions) is way too low for the pump's capacity (Approximately 4' head, and the two zone lines are 5', 1" vinyl flex lines into 3/4" manifold lines).
<Yes>
The pumps documentation calls for a minimum 1-1/2" input and output lines, on 1" threaded fittings.)  I expected noise from the pump, but it's WAY too loud for a living area.
<Time to trade this pump in for something smaller, more quiet... or...>
We have fan and round nozzles for the LocLine valves, not yet installed, and I understand that, with a nozzle restriction that even though flow will not increase,
<It will decrease>
water velocity should.  The other option we're considering is restricting the 3/4" lines at the output to 1/2", and switching to 1/2" LocLine valves.  The idea behind valves with nozzles at each of the outlets is to be able to control and direct flow in the display tank.
The overflows seem to be working correctly, what suggestions would you have for the return situation (pump, flow, noise) ?
<... trade this pump in... or add overflow capacity... these are your two options. Bob Fenner>

Complicated calculations of water flow 8/4/05
Even after reading hundreds of FAQs about plumbing I am still trying to figure out the step by step process of flow calculation.
<Mmm, there are works (printed) re such subjects>
My goal: 3000-3500 gph system flow, 220 gallon main tank, 20x5" overflow with two 1.5 inch bulkheads and two 1" bulkheads (considering using all of them as drains) I decided to go to a larger sump to handle this flow rate and minimize micro-bubbles so it will be 55x25x25 which will give me at least 100gallons of usable volume
<... and not running all this flow through it...>
Calculating head pressure at RC got me nowhere because I intend on installing a large (many t's) output flow manifold, as well as 2 lines for 2 sea-swirls, further complicating the calculations are T offs from the output of the pump for the chiller, and the large refugium. Also the many uses of 90degree elbows since all the equipment will be in another room behind the main tank, and the changes of pipe diameter going to the manifolds, chiller...etc...
<Yes, gets involved>
I am upgrading to a Sequence Hammerhead which does 3600gph at 15feet of head pressure. I am guessing this will be more than enough power...the top of my tank is 6feet high, pump is on the floor...
<Yes, sounds about what you're looking for>
After talking with Rich Durso, he mentioned two 1.5" bulkheads (with a proper overflow) should be capable of 3000gph or more,
<I would rather have two, even three two inch lines...>
I am thinking of using all four (the two 1' bulkheads also) because of restricting issues such as 90degree elbows, running the plumbing back 12 ft of so, and the use of micron bags...etc...
<Pi R squared... what's the relationship twixt the one and one and a half inch lines in terms of surface area? Surprising, eh?>
He stressed that having 4 bulkheads with Durso standpipes will be very tricky to manipulate the air intake (because one would not know which pipe to adjust...
<What?>
meaning lots of trial and error...)and may lead to 'the flushing effect'
<With this much flow through these four proposed lines... undoubtedly>
  He further recommended I try going with just the two 1.5" inch drains first then if I need more flow to add the other two 1 inch drains. But how can I calculate what is really happening as far as flow?
<See the references cited on WWM re>
I have seen people mention calculating out coming water out of the pipes by timing flow into a measured container. Is this done by filling the overflow and letting it drain through the bulks naturally, measuring the water at the end of the plumbing before it goes into the sump?
<This is one approach, yes>
This would be just the gravity part of the flow, right?
<Yes...>
The pump's draw would increase the flow drastically by sucking the water through,
<Uhh, no>
but how do you measure this once the sump is full and running with the pump on?
<Can only be approximated... but there are other means... flow gauges, dilution of dyes and use of colorimetry...>
Lets say I go with the 4 drains, the manifold, sea swirls, and everything else, with a valve on the output side of the pump just in case too much flow...
<Good idea>
bubbles...etc... After it is set up, how can I find out my net GPH flowing in the system?
<For you, perhaps a simple corrosion-proof flow gauge is best>
This is a mystery to me, perhaps you can shed some light on it for me.
Will it be a nightmare for me to go with the 4 drains and try to get them all to work properly and quietly with Durso-standpipes?
<... the number, size is of no consequence in terms of "adjustment... they are independent of each other...>
Is there a better method I should consider for draining these bulkheads quietly/efficiently?
<... yes... posted on WWM...>
Your help is very much appreciated! Also, thank you to Bob F. for recommending the LFS:  Aqua Touch, here in AZ. This will be a huge help!
:)
<They are fine fellows, very good practices... knowledgeable. I would see them... in person... re your plumbing design... I would figure out how to add more surface area to your drainage here... at least two two inch inside diameter through put... may require capping, re-drilling... If/when in doubt, read here: http://www.wetwebmedia.com/plumbingmarart.htm
and the many linked files above... you will understand, through study, what your options are. Bob Fenner>
Keep up the good work,
Nic

Overflow size related to bulkhead flow 8/2/05
Hi Guys,
I love this site! I have learned SO much over the past 2 months from reading all these FAQs, actually, the more I read the more I stall in the setup of this tank- I want to get it all perfect.
<There comes a time...>
I am still in the planning stage of my 'dream' reef tank. So Far, I have the following: 225gallon (72x24x30)acrylic tank, 48X20X20 acrylic Sump, Euro Reef CS 12-2, Sequence Barracuda pump.
<How nice>
I am fortunate to have a small bathroom on the other side of the wall where my tank will be. This will be a dedicated room for extra gear: the 1/2 hp chiller, the RO/Di, a salt water holding tank for water changes, and now my latest idea- a large refugium with a DSB, some live rock and plants and lighting.  
<Great>
I plan on having 1/2 inch of substrate (for looks) in the main tank, mostly because I prefer to save the 6" in space on the bottom of the display tank.
Ok, I had the builder upgrade the plumbing, so the tank now has two 1.5" (id) drain bulkheads and two 1" returns through the bottom of a 20"x5" overflow in the center back wall of the tank. The returns are set up to have PVC pipes coming up through the overflow then up and over into the tank.
Now after reading more, I have decided I want even more water flow than the two 1.5" drains, and possibly, two separate pumps- one for the sump (where I will have the skimmer and lots of LR, and another for the refugium. So here is my plan: I am thinking of using all four holes at the bottom of the overflow as drains. I was thinking of plumbing the two 1.5" drains plus one of the 1" bulkhead to go the sump, returned to the tank by the Barracuda pump via a manifold (with many adjustable outputs) lining the upper rim of the tank. Now the other 1" bulkhead I was thinking of plumbing it to drain to the room behind into a 65-85gallon refugium, then pumped back to the main tank via another external pump using another manifold that would go down along the side of the overflow, across the bottom of the o.f. and back up the other side of the o.f. to complete the loop. This 2nd manifold would have outputs directing water flow behind and through the LR, along the back wall and along the
bottom. What do you think? Overkill? Would you do it in another way?
<Sounds like a very nice change, upgrade>
Does this sound like it can work? When upgrading my plumbing, the builder of the tank (who thought 1" drains and 3/4 inch returns was plenty of flow-ha!) said that the overflow needed to be made larger as well in order accommodate the extra flow of the 1.5" drains. This is why it is now 20"x5" Can I use the other two 1" bulkheads as drains?
<Sure>
Will this overflow provide enough flow for all four drains like I would like to do?
<Yes, likely so>
If not can I modify this overflow by drilling a few holes in it toward the top to let more water flow in to the drains?
<Can be done... use a sharp bit, tape over the area/s to be drilled, use a variable speed drill... go slow, low pressure...>
Will the overflow/water draining in be more noisy with these 4 drains?
<About the same>
Thank you so much for your help, you guys are doing an amazing job. I would be lost without your help (the LFS here in AZ is clueless,
<Actually, there are some great shops in the area... are you familiar with Aqua Touch? and Kingsley's out there?>
they never even heard of Euro Reef skimmers or Sequence pumps)
Regards,
Nic
<Ah, wherever the info., inspiration come/s from... Bob Fenner>

Flow question 8/4/05
I have a 180 gallon reef ready Oceanic tank with two overflows, each has a 1" and 3/4" bulkhead.  I built a Durso standpipe to use in each overflow attached to the 1" bulkheads and each of the 3/4" bulkheads is fed by a mag drive 1200 pump.  This has been up and running with no problem (no fish yet, still cycling) but when I told someone at the local fish store he said the flow from the mag pumps is too much and that the drains couldn't handle it.  Well, it is handling it but I wondering if this is a disaster waiting to happen.  If so beings I already have the pumps I would like to stick with them and perhaps convert the 3/4" bulkheads to drains as well.  What are your thoughts? <Since the "Dursos" essentially act as siphons, <<Mmm, no. RMF>> they can handle much more flow than a standard drain.  The problem is that any small obstruction (snail, algae, etc.) could back the drain up enough to cause a flood.  If this was my tank, I would use all of the available  holes as drains and plumb the returns over the back edge of the tank.  Another option is to maintain a water level in the sump that is low enough that the pumps would run dry before the tank overflows, but this is often impractical.>
BTW the pumps sit directly below the tank, one pump has about a 6' vertical rise while the other has a 6' vertical and 5' horizontal run.  I'm not sure how much head pressure that creates and maybe makes the flow acceptable for my drains (i.e. I'm not sure what the flow rate is for the mag drives with the amount of head pressure).  D'Wayne  <I am pretty sure that Mag-Drives are rated at 4' of head, so you probably are achieving close to the rated flow.  Best Regards.  AdamC.> <<These tanks/lines are decidedly NOT "reef ready"... too few, small diameter... I would have re-drilled or added to. RMF>>

Overflow Box 7/25/05
I am very new to this and I just decided to switch from a canister filter to a sump since my tank is not drilled I purchased an over flow box now I cannot make it work can you help me?? Bobbie Jo <Bobbie Jo, don't know what you are having trouble with.  I'm guessing you can't get the siphon started.  Need to fill the overflow box with water, put a flexible airline tube into the siphon at the very top of the curve, then suck the air out of the siphon tube and remove the air line.  Siphon should start working.  Also try and contact the manufacturer for help.  James (Salty Dog)>

Overflow Box 7/25/05
Thank you for the help I don't know why they don't send directions thanks again.
<You're welcome. James (Salty Dog)>
Bobbie Jo

Stand integrity, Hole cut-outs around and tightening of bulkheads 7/23/05
Hi guys, and thanks for all of the great advice so far.
<Hi Randy, Ali here>
I am ready to cut the top of my diy tank stand to accommodate the bulkheads from my tank.  I have some questions about how much room I'll need around the bulkheads.  Here is a picture of the bulkhead nuts sitting on top of the stand http://home.cfl.rr.com/homebrewed/fish/180-039.jpg .  The stand top is about 1" of plywood, then there will also be a 3/4" layer of Styrofoam under the tank, so the bulkhead nuts will be stuck way up inside the part I cut out.  Can you picture what I'm talking about?
<I think so...>
I was planning to start with at least 1" of clearance around the bulkhead nuts.
<1 or 2" of clearance would be fine, I doubt cutting the top of the stand to create a 2" of clearance would hurt the integrity of the stand. Additionally, it sounds as if you have a frameless (Lee-Mar style) tank, if this is the case then as long as the tank is fully supported on the corners, then the bulkhead cut-outs won't matter as much, go ahead and start cutting :) >  
But do I need to get some type of tool on the nuts to tighten them down?  I don't think I'll be able to hand tighten them very easily since they'll be surrounded by plywood.
<No tools necessary, good ol' fashion hand-tightening them would be fine. Even if it's just using the tips of your fingers to tighten them, drink some Gatorade and flex your muscles - YOU CAN DO IT!>
Just make sure the I don't want to cut out any more material than required, since I'm concerned about the tank top bowing in the area around the cutout.
<As long as the tank is properly braced at the top, bowing shouldn't be a real concern>
Thanks!!
Randy
<No prob, good luck Randy. - Ali>

Plumbing suggestions? 7/21/05
Greetings Bob and crew...
<Sam>
Suffice it to say that you guys have been quite helpful in the past, and continue to provide an incredibly valuable service to the hobby.  Thank you.
<Welcome>
I'm getting really tantalizingly close to being ready for live rock (happy dreams of LR critters poking around), and just have this one, last plumbing issue before all of my ducks are in a row.  Would like to see if I'm on the right track.
<Sure>
Here's what I've got.  125 gal tank.  1" drain,
<Only one?>
with a Durso standpipe.  The drain hits a T which routes water to the sump for processing, and also
splits water to the refugium, which gravity feeds back into the sump.
Return water is pushed back to the tank via an Iwaki 30RLT, which is linked to a SCWD, returning water alternately to two 3/4 inch returns.  All plumbing via vinyl tubing.  Limiting factors as I see them are the 1" bulkhead on the drain, and the 3/4 inch connections on the SCWD, necessitating 3/4 inch returns.  Additional current via a PanWorld 50 PX-X (1100gph) feeding a closed loop.  
<I do wish... you had two 1 1/2" drains, two 1" returns...>
Here's what's happening.  With about four extra inches of water in the sump to prime the system, I'm able to raise the water level enough that water is returning via the drain.  However, even as the water is returning from the tank, the pump is pulling enough water that the sump level is falling below the pump intake, resulting in lots of cavitation.
<Trouble... drain lines too small, sump too little water for transit volume>
  Looking at the 1" drain tubing, its not draining at the full capacity of the tubing, which is the same diameter as the opening in the bulkhead.
<... a common misperception... the line doesn't "suck" water out of the tank... water has to "pile up" higher... drain>
My first thought was that the pump was pushing more water than the drain was capable of handling.
<In a manner of speaking, yes>
I now am not convinced that this is the case.
Considering the SCWD, the 90-degree fitting on the openings of the 3/4 inch returns (and the spring activated check valve) I've got something like 9 feet of head according to Reef Central.
<The model there is necessarily a simplification>
  Looking at the spec.s on the 30RLT, with that much head pressure, I shouldn't even be approaching 600gph, which I believe is somewhere in the area of the max capacity of the 1' bulkhead.
<Uh... no... there are a few very important (co)factors involved... the vinyl tubing has some induced drag, the extent of the horizontal run from the bulkhead...>
I'd considered slipping a gate/ball valve on the output of the return pump, but really don't think that's the answer.
<It is not>
  Perhaps I need a slightly larger hole in the cap of the standpipe?  Or perhaps just adding a few more gallons of water in the sump for the pump to prime the system?
<No my friend... the root of the problem here is really the lack of size, number of through-puts... you won't be able to get enough water through what you have>
This is my first foray into plumbing an admittedly rather intricate system, and as such, would be interested in any suggestions you could provide.  Am also curious if there might have been value in hard plumbing the system,
<Yes... in some cases, some flexible is a good idea... but in most... rigid is preferable... for how many reasons?>
as it seems like there might not have been as many issues utilizing straight lines and angles.  I assume that that the other side of that sword is that with the vinyl tubing, I likely have less head pressure than a similar set up using elbows.
Thanks in advance,
Sam King
<Sam, do read over the Plumbing materials we have archived on WWM... there's a bunch. And do have some other folks with similar systems chat with you re yours... I would have the tank drilled for two 1 1/2" bulkheads (two inch diameter) and use the existing through-puts for returns. Bob Fenner... who has "been t/here, done this... many, many times>

Re: Water Return Manifold 7/20/05
Dear Mr. Fenner,
    Thank you for your advice.  But speaking about water returns I was reading through a lot of messages on WWM and saw a large number of messages that complained of sump overflows during power failures.
<Mmm, real overflow "boxes" take account for such failures... they don't lose siphon>
  Since I also live in an area where we experience frequent power outages (rural Montana) I had to find a cure for all the spilled water.
<... principally adequate (large) size/d transit volume sumps... not filled to capacity...>
Since I use an older 30 gallon glass tank, drilling was out of the question.  So I use the dreaded J-tube as my sump intake but instead of letting gravity do all the work my intake is connected to a Quiet One 1200 pump.  It pulls the water into the sump but shuts off during a power outage.
<Mmmm, I would NOT do this... far more trouble to be had...>
And with a small hole drilled in the
J-tube slightly below the display's water surface it eliminates back siphoning.
<What if this becomes occluded...?>
The sump's output is also connected to a Quiet One 1200 that (was) returning through a spray bar with a hole drilled below the surface.
So I can leave my sump almost completely full and not worry.
<... no...>
  By utilizing
2 identical pumps I found a cure for my woes.  Plus there is very little adjustment needed since they both pump the same amount.
<Almost laughable... but, "you'll learn"... Have seen, read about such arrangements... many times over the years... they eventually fail, flood floors>>
  I just thought I would try to provide a little info and some feedback to you guys for others to whom drilling is out of the question.
<My emphatic message to all others who read this: DON'T try it>
  Though, there is some caution to this tale.  I don't recommend it for the lax reef keeper (If there really can be such a thing) Because the pumps must be cleaned religiously in order to keep them both working in prime order.  If only one stops...it can be potentially disastrous unless you use a very short intake tube.  (I know that from experience... )
Best Regards,
Andrew
<You'll see... Bob Fenner>

Re: Water Return Manifold 7/20/05
I agree very much with Bob... to the extent that I have repeated darn near a mantra on such matters that I would rather have no sump at all than use any kind of siphon overflow. Put another way, I don't want to sleep in a house that has a siphon overflow. As Bob says... they WILL fail in time. And beyond flood, there is fire hazard at times. I have seen this on one occasion thanks to a siphon overflow.
Don't do it mate. The downstream features are not that badly needed nor so difficult to plumb upstream [the display may be inconvenient to drill... but a refugium or reservoir next to and slightly above your tank can be drilled to hold refugium life, skimmer, Ca reactor... anything that you would have fed with a siphon overflow)
Please(!) reconsider. Anthony
<Thanks for this Antoine... thought you might want to see, respond to this ongoing corr. BobF>

Re: Water Return Manifold 7/21/05
Dear Mr. Fenner,
Please forgive me for even causing you to post this on WWM.
<Mmm, no worries... we post most all.>
  I have only had the system running for 2.5 months and haven't had a problem yet.  I had no idea that it could actually pose a risk of disaster.
<Oh yes...>
  I am relatively new to the hobby and the only thing that had been recommended to me was a J-tube setup by an aquarium store which I no longer shop at. I didn't know about putting the sump above the display.
<Is generally safer... if practical to situate it so>
Anthony mentioned this, and I would like to know how it is done.
<... is posted... in places on WWM, our latest book...>
  If you could briefly explain it that would be much appreciated.  Also, please don't post the letter if it may lead others into believing it will work.
<Not to worry... You've likely saved a few lawsuits, broken marriages... and more...>
  I would hate to cause someone else to make a potentially disastrous mistake.
Sincerely,
Andrew
<There are many ways to learn Andrew... direct experience of larger scale mistakes is not a good one. Bob Fenner>

Overflows vs. Closed Loop 7/16/05
Good day,
<And you>
I really should be charged for all the questions I have been asking lately.. so please feel free to let me know where I should deposit the money and how much :-)
<We never turn down the cash!>
At the moment I wish I never heard of "closed loops", because I am really battling with this. I'm setting up a new 150 Gallon reef tank and have really struggled a lot to sort out the water circulation. For my overflows I have 2 x 1.5inch bulkhead drains (inside diameter). From the sump I have a pump that sends about 1500gph into 2 x SCWD for the return. The overflows seem to handle this quite easily, with no problems so far. The problem I have is with the additional circulation. My original plan was to use an "over the top" configuration for a closed loop, where I don't have to use drilled holes. I'm finding the plumbing for the closed loop very difficult to do, the tank braces and "lips" makes life a little difficult with the "over the top" type setup, I'm finding it very hard to find the proper parts, ball valves etc. and I also have some space problems below my tank.. I'm very frustrated at the moment.
<Seems so>
So now I'm thinking of drilling an additional 2 x 1.5" holes to cater for the intake of the closed loop. At least this will eliminate the need for "over the top intakes". The one thing I would really like your opinion on is the following - The one place I do have a lot of space in is the "return chamber" in my sump. The total sump size is about 65 gallons, with the return chamber on its own taking up almost half of that. So the one option I was considering is - instead of using the 2 additional holes for a closed loop, rather add them to my current overflows and add the second pump to my sump. This way I will have 3000gph going through my sump/overflows with 2 return pumps and no need for the ball valves and other things I've been struggling with so much on the closed loop. I can split the overflow lines so that only part of the 3000gph goes through my refugium area and skimmer and the rest straight into my pump return chamber, so I'm not much worried about sending too much water through my refugium.
Do you think the option of using more overflows with 2 strong return pumps instead of a closed loop for 3000gph be a bad idea?
<Mmm, no>
Should I rather bite the bullet and continue my struggles to get the closed loop going?
<Up to you of course>
Is 4 x 1.5" holes too much for a 150Gallon tank ?
<Mmm, no>
Ps. I will connect the second pump to another 2 x SCWD, so the actual flow rate will be a bit less than 3000gph.
<Okay>
Any advice will really be appreciated.
<Perhaps a good idea to "step away" from this project for a while... Come on out to HI next month and go diving with me... all will seem clearer with a bit of a holiday away. Bob Fenner>
Many Thanks
Chris

Overflows / Dual Standpipes - 07/09/08
My 90 gallon oceanic has the typical holes for a 1 inch overflow and a 3/4 inch return.  If I utilize both for overflow, would each Durso standpipe have to be EXACTLY level with the other to ensure that they both work right, or might one be plumbed a little lower/higher than the other?
<<Exactly?...no.  But the should be very close unless your return pump will not exceed the capacity of one and the other is just used as a failsafe.>>  
Any issues you see or I should be aware with respect to the actual rigging up of each standpipe?  My reasoning for using both as overflows isn't really to increase flow, but to serve as something of a safety design to minimize the hazard of one drain clogging or otherwise failing.
<<Ahh...ok.>>
Basically, I'd have the flow set at an amount that the 3/4 could handle alone at say max capacity, that way I'd effectively have each pipe able to support the other's failure.  Plus, I was intending to have the small hole run to a refugium, the other to the sump.  Thoughts?
<<Mmm...if your plan is to have one supply the 'fuge and the other supply the sump, I would install them level/equal and use a return pump that will load both at about HALF capacity combined.  This way you supply better flow to both while allowing a buffer for safety.>>
Thanks.  
<<Regards, Eric R.>>

Overflow Box 7/9/05
Dear WWM Crew,
<Glenn>
I'm looking into building a custom over flow box and have questions on what its dimensions should be to handle the water flowing through it. A year and a half ago, I decided to add sump/refugium for my 75 gallon aquarium. I decided to use the skim box that came with my Remora Pro (The one for the Mag 3 pump) as the overflow. I used silicone to seal off the pump side and return sides. I had my tank drilled in the back about 2 - 3 inches from the top and 2 - 3 inches from the left side (looking front). The bulkhead runs through the tank into the box, which is held in place by silicon and the bulkhead. I estimate that this drain runs 350 - 375 GPH through the sump / refugium. The Skimmer's Mag 3 pump sits in the return side( I had to cut out the outside panel of the return side to fit the pump in there.
<Innovative>
Now I would like to replace this box, with a box that will hold both the overflow drain and skimmer pump. The reason are for skimmer efficiency and appearance. I recently read a Reef Central thread from Anthony explaining how to help your skimmer collect more skimmate. For HOB skimmers he said to move the pump as close the surface as possible.
<Yes... more of the phobic molecules there that you want to remove>
This one came with a skim box and I simply want to get that back. I don't want to tear the tank down again (Cause I have a DSB), so my plan is to drain the tank to a few inches below the drain. Remove the old box and bulkhead and add a new custom box that will house both the drain and skimmer pump. My question is how to figure out how much collection surface area this box will need and volume to keep up with the 350 GPH drain and up to a Mag 5 pump( In case I decide to upgrade.) So it would need to continually intake 700 - 1000 GPH without ever running dry. The current box is (L x W x H): 10.34" x 8" x 4.25"). Of course only about 2/3 of that is used by the over flow. Thanks.
Sincerely,
Glenn Serpas
<Mmm, "bigger is better" is about the simplest, best statement that can be made... Please see WWM re relative sizes of bulkheads, other considerations for allowing this much flow... and safety measures should it get blocked, water level drop... Bob Fenner>

Bulkhead - 07/01/05 actually transit volume in tank/sump... mis-matched
Good day,
<<Hello!>>
Once again I have only one place to turn to for help. (Thanks again for all your support and advice).
<<Our pleasure.>>
I have been struggling with this for days, read a multitude of FAQ's and still can't figure out what I'm missing.  I'm busy setting up my new 150 gallon tank and I just can't figure out how to make the bulkhead overflows work properly.
<<Okay?>>
I have 2 x 1.5" (or 40mm) bulkhead fittings high up in the back wall of the tank.  On the inside of the tank nothing is connected (its just 2 holes with "tank connectors) <<Intake screens?>> and on the outside it's connected to 90-degree elbows which connect to the pipes going down to the sump.
<<Sounds fine so far.>> <T's with their open ends open to the air would be better. RMF>
The inside diameter of the bulkheads and all pipes is 40mm (or 1.5").
<<Good to hear...bigger the better.>>
I was under the impression that these 2 simple holes in the tank will easily drain 1000gph, so for the return pump in my sump I bought something that pumps at 1000gph.
<<Yes, I too would expect the pair to handle 1000gph.>>
Now, when I switch on my pump in the sump, the following happens - as the water level rises, it starts flowing into the two drain holes an down into the sump. However, the draining starts slowly at first and only increases in tempo as the water level rises.
<<Yes...takes some water pressure to overcome the air pressure in the lines.>>
When the water level becomes high enough so that the overflow holes are about halfway submerged, the overflow starts matching the rate of the inflow from the pump.  The problem is, by this time the return chamber in my sump is empty and the pump starts sucking in air.
<<Simple matter of your sump not being large enough my friend.  The sump should be big enough to hold a "working" level/quantity of water IN ADDITION TO the "drain-off" from the tank when the pump is off.>>
Now unless I'm making a really stupid mistake somewhere it seems that with these bulkhead overflows you have to push quite a lot of water into the tank first before the overflow "kicks in".
<<Laws of physics at work here.  You might ease/help things a bit by aspirating your return lines.>>
Can you perhaps give some advice here ? How do you normally set up these bulkhead overflows?  I believe that the inside of the bulkhead is sometimes connected to an elbow that bends up, but unfortunately this is not an option for me (because the holes are quite high up on the tank wall).  
<<A bottom drilled tank with overflow box "might" require less water volume to get things going due to rapid build up of water height (weight) in the overflow box...but you haven't done anything wrong here, you simply need a larger sump volume of water.>>
Am I just missing some simple concept here or do I just need a much larger sump to cater for the initial "kick off" of the overflow
(Really didn't think my sump was too small)?
<<I think for this application your sump is too small.>>
Your help will be very much appreciated.
Thanks
Chris
<<Regards, Eric R.>>

Re: Bulkhead - 07/02/05
Thanks a lot Eric, I don't know where some of us would be without your help.
<<Always a pleasure to assist <G>.>>
Have a good weekend.
<<And you too.>>
Chris
<<Eric R.>>

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 and Plumbing Flow Rates -
How much over flow (max) do you feel a 1.5 inch overflow can handle, per hour? <Well... please keep in mind that these are two separate questions. A 1.5" piece of tubing can flow roughly 3,500 GPH. The "overflow" may [in fact probably will] limit this by the size and number of slots that allow water to pass through it.> Now, how much do you feel it should handle, being conservative and safe? <Again, depends on the manufacturer of the overflow.>
Same questions for a 3/4 inch overflow (for a 90 gallon oceanic, drilled with a 1.5 and 3/4, I was contemplating using both for overflow, but at a rate well below what each could handle collectively). <Not entirely sure. Know that Oceanic/AllGlass have improved their overflow boxes to handle higher flow rates, but you should really get in touch with them to see if their overflow box will in fact handle what you're looking to push through it.> hear that 1.5 inch can max out at 750 GPH, maybe I'm wrong. <Do believe it's more that that. The old style AllGlass overflows could handle 900 GPH per overflow box, the Oceanic ones could handle about 1200 GPH> Not sure of the safe/reasonable level. <Again, should contact the manufacturer.> I haven't seen info. on a 3/4 as it relates to "overflow". Thanks very much.
<Cheers, J -- >

- Overflow Box Design -
Good afternoon crew,
I am in the planning stage of building a DIY internal overflow box. The design of the box is attached. Could you kindly look over the design and tell me if I have any design flaws? <I like it. I'd say it will need testing as having a pump running on a gravity feed from that siphon (I'm referring to the closed loop line) may run the box dry. Likewise, if the siphon were to break, you could damage the pump. Would probably be better to get the tank drilled for a bulkhead just below the water line and allow the closed loop pump to stay wet all the time.>
Thank you in advance,
Rainer
P.S.: Many of my e-mails don't seem to get to you - is there some type of block or problem with programs you are aware of? I am not complaining, just trying to find a solution. T.Y.
<Have no explanation for this. We do block excessively large attachments, but other than that... wouldn't know where to point the finger. The Internet is a big place and there are many places where email can fall on the floor. Cheers, J -- >

Tank Drain Size And Overflow vs. Closed Loop - 06/20/05
Hi Crew, thank you all so much for your website and personal advice!
<<A pleasure to assist.>>
I'm overwhelmed a bit, but trying to read all that I can.  My original plan was to use a somewhat beat up used tank, but now I've decided to buy a new 180g tank from www.glasscages.com.  I can have it drilled custom, so I have some important decisions to make in the next 2 days (have to order first of the week to have it on their truck coming to Orlando).  
<<OK>>
I'm doing a tank that is viewable from both sides and one end.  I think that the whole "back end" will be totally closed off by the overflow wall.   I want to be able to do 20X flow without powerheads.  On my 180g that amounts to 3600 gph through the sump if I don't do a closed loop.
<<Mmm...I'm leaning towards the closed-loop with a separate return pump for the sump in the 700-900 gph range.>>
Is it realistic to put that much flow through a 24" long built in overflow and then run it through a 36x18x17tall sump (I'm ordering that tank also)?
<<Can it be done?...probably.  Would I want to do it?...nope.>>
It seems a little scary to me!
<<Me too <G>.>>
Will it be too much flow for a refugium to be incorporated into the sump?
<<Would likely "wash all away".>>
If I don't pull it all through the sump, I'd need a closed loop, but I don't have any "back wall" space to drill for a closed loop.  Is it a bad idea to try to do a closed loop that pulls from the overflow area?
<<Actually, my suggestion would be to pipe the intake for the closed-loop in through the bottom of the overflow box, split it in to multiple intakes (2 minimum, 3 or 4 better) all the same diameter as the pump intake pipe (in other words, don't "reduce" the size), and plumb these through the sides of the overflow box so only just the intake screens protrude in to the tank itself.  This will alleviate any concerns of the overflow handling the volume of the pump for the closed-loop...and the multiple intake ports will keep that 3600 gph pump from "straining" all your critters through the intake screens.>>
If I don't pull from the overflow, my only other option is to pull from a standpipe somewhere out in the tank (there is NO "back" of the tank available for drilling).  If I'm pulling from a standpipe around the middle of the tank, I'm worried that critters and stuff will constantly be getting trapped against the intake.
<<A possibility, but can be addressed with more/multiple intake ports to create a "more gentle" flow through any one port.>>  
Next question - hole sizes.  According to the RC calculator, I can get 1400 gph from a 1.5" drain and 2400 gph from a 2" drain.  I was planning on doing two 2" drains and one 1.5" return all drilled inside of the overflow.  That is a lot of flow potential but I'm not sure if I can pull that much flow over the overflow without it sounding like Niagara Falls.  What is your opinion?
<<Exactly...another reason to go with the closed-loop for the bulk of your flow.  I do like your hole sizes, bigger is always better...if only for that margin of safety (sooner or later something WILL restrict/clog a drain.).>>
Also - I may go to two 1" returns so that I can have two pumps.  This seems like it opens more options as in one pump being a closed loop, and some redundancy in case I have a problem with a pump, etc.  What do you think of that idea?
<<Two returns is fine, but I would use one for the closed-loop and the other for the sump return (as mentioned previously).  As far as diameter goes, use what is specified for the pumps you will be using.>>
Thanks again for all of your hard work to promote this hobby.  
<<Hope this all makes sense.  Try some key-word searches of our plumbing FAQs re "Closed-loop" and "drain size" for additional info.>>
Sincerely,
Randy
<<Regards, Eric R.>>

Drain Size and Noise - 06/16/05
Hello WWM crew.
<<Evening>>  
In a response, Anthony stated "1" bulkheads really should only handle about 300 GPH each to be safe and quiet. Thus... to run a 1200GPH pump, you need 4 bulkheads! With your 1.5 inch holes... I'd guess you could only run about 1000PGH through them quietly".  I also read somewhere else on the site that a 1.5" drain can handle ~750 gph.
<<I agree with Anthony's estimation.  I originally set up my tank with six 1" return lines and a 1500 gph pressure-rated return pump...still made so much noise you couldn't hear the television or speak in normal tones, even after aspirating the return lines.>>
If I drill two 1.5" drains to my sump, will they be enough to handle the ~1500 gph total of my 2 sump return pumps?
<<Probably...>> <Mmm, not IMO/E... two 2" lines, vented, maybe. RMF>
Would a gate valve placed after each pump be good for "dialing back" if necessary?
<<Always a good idea...along with unions to facilitate maintenance.>>
For my closed loop system, I was told the size of the drain should match the input side of the pump (1200 gph), which is 1".
<Yes>>
But a 1" drain handles only 300 GPH quietly.  I'm confused.  Wouldn't it be better to have two 1.5" (or one 1.5" and one 1") drains joining at the closed loop pump to get ~1500 GPH?
<<Fluid dynamics can be a funny thing to understand.  The 300 gph recommendation is for GRAVITY overflows/drains.  When the water is forced under power/pressure as when the drain connects directly to the pump the "dynamics" are totally different.  As long as the piping is of the diameter recommended by the pump manufacturer the pump will move the listed amount of water (taking head-height and possible exaggeration on the part of the manufacturer in to account, of course); and any noise, as long as you don't have air being sucked in through plumbing/pin-hole leak, is generally just that of the pump itself.>>
Thanks
K
<<Regards, Eric R.>>

Tank drilling - size and position concerns
Hi guys!  You all are doing a great service to the hobby!  Here comes one more person jumping in...  I have been researching and reading a ton of information here, at ReefCentral, and elsewhere...  
<Good>
I have recently bought a used 180g 6'x2'x2' tank.  The goal of this tank (my first marine tank) will be FOWLR with the intent of a reef a few years down the road. So I want to set some things up with a reef in mind.  Right now I really only want to address drilling additional holes in the bottom of this tank and the associated overflow.  The tank currently has an end overflow with three 1.75" holes drilled in the bottom.  I am concerned that I will (eventually) need more flow than these holes will allow since I will be limited to three 1" diameter drain pipes and will have to pipe the returns over the side (not my favorite config).  I'm assuming I can get about 1800 gph with three 1" drain pipes.
<At the most, yes>
I know a company that will drill additional holes in the bottom (not tempered), but I'm concerned about the strength of the 3/4" bottom glass.  Here is a photo of the tank and a CAD drawing of the current and proposed holes:
http://home.cfl.rr.com/homebrewed/fish/tank_holes.jpg
http://home.cfl.rr.com/homebrewed/fish/tankbottom.jpg
<I see>
Would you suggest moving the new holes further from the existing?
<Yes>
  Make the new holes bigger?
<Yes>
Any other helpful suggestions would be appreciated.
<I would make the new holes two inches in diameter and move them midway twixt the wall and existing nearest hole, and slightly further (another inch or so) away from the side... much could be said re glass properties... super-cooled liquids period>
The RC calculator tells me I should have 27" length overflow.
<?>
However, I think I have to go straight across the 24" width if I add holes.
<I would stagger the new holes as mentioned>
If the overflow turns back to the end wall instead, will I end up with a dead zone that collects debris?
<Not with good circulation otherwise, and careful rock, decor placement>
The last question is regarding the return line diameter.  If I have a total of five 1" pipes through the bottom, I think I could do four drains and one return.  I want to take the return water up to the rim of the tank, split it along each 6' side with a few outlets along each side.  Would a single 1" return pipe be sufficient to handle the return water for the whole system (4 drains x 600 gph = about 2400 gph)?
<Mmm, better to use two or all three of the existing lines here... devise a return manifold for front, back with the two outer ones...>
Would I be better off just using the three holes as-is with two as drains and one as return, then adding some Tunze pumps for additional flow?
<Mmm, no... insufficient diameter... a noisy mess now and frustrating, potential trouble...>
The last question - is there any way to get a larger diameter pipe safely through that 1.75" hole?  I'd love to be able to use a 1.25" pipe with the 1.75" holes, but my understanding is that I can't do it.
<Can "cheat" and use thinner through-hull fittings, smaller schedule plumbing (like 200 PVC... as in rated for 200 PSI... instead of 40... for 400...), but don't do this... Much better to have new holes made. Bob Fenner>
Thanks,
Randy

Horizontal Overflow - 06/10/05
I'm planning on having a 55 AGA drilled on the top back wall for two or maybe three 1" bulkheads just below the frame.  I want a flow rate of at least 600 GPH and hopefully more like 900gph.
<<I would put four drains of this size on this tank.>> <RMF would use 1 1/2" through puts>
I want to install a glass or acrylic skimmer box that extends the length of the tank (48") and be approx 1/2 to 2 inches wide and perhaps five or six inches deep.  This will be siliconed to the back wall and the bulkheads will remain inside this zone.
<<Go with glass...much better adhesion with the silicone.>>
My questions are:  1.)  Am I correct in my assumptions about flow rate from this number and size bulkheads in this application?
2.)  At this level of flow will there be much noise or do I have to install some type of silencer?  i.e. external Durso standpipes?  3.)  Should I install some sort of teeth or mesh to keep out snails etc?  Depending of course on if I need to install elbows on the bulkheads for noise issues.  And finally what type of flow rate will I need from my pump.  I was considering a Mag 9.5 or 12.  I know I can throttle the pump back but will an undersize pump be a better choice?  Like a Mag 7?  Unsure how to proceed and thanks for the help...!  Glenn
<<Most folks underestimate what their drains can handle.  Just because a drain is supposedly "rated" for a certain amount of flow doesn't mean it will do so with any margin of safety, and most assuredly it will not do it quietly.  Do some reading here http://www.wetwebmedia.com/overfloboxfaqs.htm and at the associated links in blue.  Much info/help to be found.  Regards, Eric R.>>

- Fish Overboard, Or At Least into the Overflow -
There are postings in WWM about fish jumping into the overflow filter, but I have not found suggestions for how to get them out (without taking down the whole system).
I have an Oceanic overflow trickle filter in an Oceanic 72 gallon fish/reef tank.  There is an extremely small gap between the cover glass and the rim of the overflow filter, too thin I would think for anything to jump through. However, I do remove the cover glass to clean it once in a while. Perhaps during one of those cleanings a Percula Clown made the leap into the overflow box. <I had a clownfish that would end up in the overflow of my 180 Oceanic all the time - once a day.> He is surviving (the last time I looked), apparently feeding off food that comes in through the three rows of drain holes at the top, middle, and near the bottom of the tank.
The box has plumbing inside it, and the clever Clown hides beneath the plumbing whenever I look down the box with a flashlight.  I only catch glimpses of him.  Without the plumbing, I could use a long handled net and return him to the main tank.  However, even if he did not hide, I have difficulty moving a net in the free space.  Any suggestions short of taking the whole thing apart? <I actually used to catch mine with my bare hand as it was easier to do and almost impossible with a net. Move slow and be patient. After a while, my clownfish got used to it and when I reached my hand in there, would just stop swimming and let me catch it. Anyway, breaking down the overflow plumbing would be a pain... would do that as a last resort.>
I've learned about plastic gutter guard and egg crate and will be installing that to prevent this from occurring again.  Also, I lost a Nudibranch to suction through the drain holes and am hoping that the gutter guard will prevent that from reoccurring.  Any pointers on where to find a design for installing the gutter guard and egg crate? <Probably just use nylon wire-ties... affix over the overflow.> I understand one is in BOCP1 but can't find it there.
<Cheers, J -- >

- Fish Overboard, Or At Least into the Overflow, Follow-up -
Thanks. <My pleasure.> It makes sense that it would be easier to catch it with the hand than with the net. Glad to know that others have had this problem; at least, I know that it is solvable. <Well... both: a rather common problem and also easily solved. Good luck catching your fish.
Cheers, J -- >

Water Flow...Not Enough Drains! - 06/09/05
Hello Crew!
<<Evening to ya!>>
Please allow me to ECHO the many expressions of THANKS from fellow readers for your help, dedication and for the knowledge gleaned from your site.
<<Many thanks, is a pleasure to assist.>>
I am in the planning stages of a 180 gal saltwater reef tank. PLEASE double check my thinking here.
<<Alrighty>>
Goals in design:
1). Maintain at least 200 gal of system water AFTER displacement of rock, sand by using a 55gal refuge (drilled 1" drain) on display next to main tank and 55gal sump.
<<Would suggest two drains here to allow for ample flow rate through this 'fuge.>>
2) Achieve a turnover rate of at least 30 to 35 times per hour(6000-7000)Super Amp Master at 0 to 5 feet head with 2-2" PVC return and 2- 2" drain outlets.
<<Do double check your figures here, I'm thinking you'll need twice the number of 2" drain lines, and even then will be marginal.  Another consideration...this much water rushing through your sump is going to make a heck of a racket.  You may want to consider a closed-loop for the big pump, with something in the 700-900 gph range for the sump return.>>
I am considering a through the wall application which would turn a walk in closet into the sump/skimmer/pump room.
<<Handy indeed.>>
Aside from the risk of divorce it would allow for 0 or very close to 0 head, noise reduction.  Delicate spousal negotiations to follow. <<G>>
3) Turnover rate of refuge 5-10 times per hour (275-550).
<<Thus the need for two 1" drains as a minimum.>>
Return to refuge with 1" PVC  "T"'ed off one of the 2" PVC returns with check valve to control flow.
<<Check valve? No...I hope you mean "gate" valve.>>
Refuge drain with 1" PVC to sump.
<<Don't over estimate what your drain lines can handle.  Best to "over engineer" here my friend.  I highly recommend you do some reading about this on our site.  Start here (http://www.wetwebmedia.com/plumbingmarart.htm) and continue with the related links in blue at the top of the pages.>>
4) Dedicate the 2-2" return pumps to overall system FLOW ONLY thus utilizing an additional external pump from the sump (probably 1" PVC) to provide water MOVEMENT in the main tank via a manifold (exact configuration and pump capacity to be decided after experimentation.)
<<Yes, the closed-loop manifold is your best bet for the high-flow pump you describe.  Much info about these as well in the links I mentioned.>>
(Any suggestions on user friendly Drawing-CAD software?)
<<Afraid not.  Try posting your query in the DIY forum on Reef Central (http://www.reefcentral.com/forums/forumdisplay.php?s=&forumid=3), I'm betting someone over there knows of some.>>
Thank You, Benjamin
<<Regards, Eric R.>>

Modify Reef Ready
I have a 75 AGA reef ready tank, it currently has a 1" drain and a 3/4" return.
<Dismally small fittings>
I'm wanting to increase flow into my sump so I can use a Mag 24 (36 would be great but probably not possible.) to power a manifold with 7 tees. Thought I could use the 3/4" return as another drain to the sump with a Durso standpipe, so I would have a 3/4" and 1" drain.
<Still way too insufficient... you need two- two inch drain lines... minimum here>
Now, what can I do/needs to be done to maximize my reef ready overflow to max out my bulkhead drains (have been reading that the overflows don't work the best). I'll use the Mag in the sump. Currently have a velocity T4 external plumbed. Reason for the modify is I want to increase flow quite a bit but want to remove my powerheads and not add more... already been established for a few years so drilling for closed loop is out of question. Thought of using my return as a manifold.
<... you need to rethink all this... either go with hang-on overflow boxes, or bite the proverbial bullet... drain the tank, have it re-drilled. You can read on WWM re... Bob Fenner> 

Re: Modify Reef Ready Turnover
Hi Bob:
<May the Force be with ye!>
Thanks for the quick reply!! In keeping with all the hoopla...I'm having a Star Wars moment. Actually speaking with the Yoda of the hobby!!
<Geez, and I can't get Di (wife) out to see Lucas' sixth and supposedly last in the series... And hey, I'm taller than two feet, and not quite as green I be>
I think that I was unclear or I am misinterpreting your answer. I'll give it another try.... When I said the tank has 2 x 1" overflows, I was only referring to the lines to the sump. The tank has two separate corner overflows, each with 1" overflow and 1" return.
<Ahh!>
I'm not sure whether that was clear. Does this affect your response?
<Indeed it does>
I get the sense that you were saying that I may be able to get the flow close with the four holes, but re-drilling would be better.
<Yes>
Thanks again for the help. Take care, Greg.
<Will endeavor to do I will. BobdaF> 

External over flow, not reading WWM, illiteracy period
I
<What is the deal with the public and the personal pronoun "I?"... it's capitalized people>
was wondering if I could drill some 3/8 or 1/4 inch holes in the back of my glass tank and then build and external over flow.
<Too small diameter. Please read here: http://www.wetwebmedia.com/marine/setup/index.htm scroll down to the section on Filtration... read re plumbing, overflows...>
I want the over flow to contain the bulk head because I do not want to drill a big hole in the bottom of my tank. also will acrylic bond to glass. Robert Tice
<... no. Bob Fenner> 

4 - 90's or Sumps, Pumps and Plumbing
Greetings to the Salty Dogs,
<Woof!>
If possible, I was hoping for a little more advice for the plumbing situation on my new tank? (My original email follows for reference.) My 90 Gallon tank arrived today and is drilled for two 2" outputs and two 1.5" returns. My sump is designed with one 2" output to the return pump. I have purchased two Reef flo Darts for the system. One for the sump return pump and one to power a closed loop. 
I am now re-pondering my original plan to use both 2" Drains to the sump and instead converting one of them to feed a second pump for the closed loop.
<You will likely need both the two inch lines to feed the sump here>
Originally, the closed loop would be fed by an over-the-wall feed pipe and the returns would be in the same manner.
<I would stick with this>
It seems like simple physics in that having two 2" pipes feeding another tank (the sump) with only 1 2" exit leaves one of the outputs superfluous. Is this the case or am I missing something in my thinking in terms of the dynamics of the pump output?
<You can try it and see...>
I do realize that the pump is adding pressure but shouldn't the gravity feed equal out with what the pump can move back up into the tank to drain back down via gravity?
<Mmm, if the pump had a very low flow rate, yes... In actual practice, pi R squared for surface area of the opening... gravity doesn't "suck" much here... especially if there is any horizontal plumbing involved...>
I'm making myself dizzy with this question.
<Take a tea break... I am>
In your opinion should I stick with my original plan and use both outputs to the sump and feed the closed loop over-the-wall and keep the redundancy to the sump or go ahead and use one drain to feed the closed loop?
<Stick with the original plan>
Thank you so very much for the help!
The Drunken Monkey
<You wish! Bob Fenner>

Water Level Fluctuation in Overflow
Dear Crew:
<Paul>
The water level in my overflow fluctuates by about an inch every 10 seconds.
<... not large enough, water level/s too low... pump/s too large flow rate/s...>
If the water level drops close to the opening of the Durso-type standpipe, an irritating suction sound is generated.
<Yep>
What can be causing this periodic fluctuation in water level?
<See above>
Why is the flow through the standpipe not constant?
<Transit volume issue. Your water is "oscillating" twixt your system above and below... due to insufficient plumbing, and/or pumping flow>
I have an Oceanic 75-gallon tank with a "Mega-Flow" overflow and an Oceanic standpipe that is similar in design to a Durso standpipe. The overflow empties into a 29-gallon refugium with an Iwaki MD-30RXT pump. I had replaced the Oceanic bulkheads with PVC connectors to increase the size of the openings by 1/4" and to increase the water flow.
<Good move. You may still need to add water (take care to measure... with the power turned off... so as to avoid flooding) to the sump... reduce the flow rate of the pump... Bob Fenner>

Plumbing and Stuff
Hey crew,
My brother is on his way up from Southern Cali bringing me my brand new 135G glass tank.  72"X18"X24".  I am gonna make it a FOWLR predator tank:
200 lbs. of Florida crushed coral substrate, is that too much?
<Try it and see... should be thin or rather deep... see WWM re>
80 lbs. of Caribbean Live Rock from Drs. F&S
Home made 40G sump w/balls
EV180 w/ Mag 7
Soooo, I was planning on using a Gen-X PCX-40 rated at 1190GPH w/22' max head for the return pump.  I will only be at about 5' of head.  I contacted the company who I bought the tank from and they said the bottom pane is tempered and the sides aren't.  The tank is a complete virgin with no holes.
  I know it is a no no to drill tempered but, is it impossible for even the pros to do?
<Can be done>
  Someone like Custom Glass?
<Or other glass companies around you... call them re>
If so, I will then have to go through the side.  I can only have one overflow because of where the tank is being placed, so by going through the bottom back of the tank, what size bulkhead would you use?  I was thinking about 2".
<Should work... if placed low enough... when/where in doubt, make it larger... can be regulated on the discharge side>
It sounds excessive, but it has to go directly into a 90 degree elbow.  Do you see any problem with that size because of the elbow?
<Will slow down flow a bit... I encourage you to use a Tee instead... for venting, noise reduction... read on WWM re>
Also it will then have to Y off to go into two separate chambers of balls.  I read over the faq's on plumbing and got a lot of mixed opinions.
<Then... keep reading till you have your own ideas of how to proceed>
I just don't want to have the wrong size hole drilled.
Now to my DIY sump.  I might have a good idea.  It's a 40G three foot tank.  
I want to use two five gallon buckets filled with bio balls.  It seems like a lot but the fish are big and messy.  My main concern is keeping the nitrates as low as possible between the faithful bi-weekly water changes.  
<Skip the wet-dry media (balls) if you want to avoid nitrate bottle necking>
Most wet/dry's with 4 gallons of media say they're good for 150G.  So by having two going, when the nitrates got too high, I could pull one bucket and clean em up while the other 5 gallons are still holding the bio load.  
What do you think?
<Won't work... but go ahead and try this... you can always pull them>
Finally, I would like to try out UGJ.(under gravel jets)  Have you heard of anyone using this idea on a s/w tank?
<Yes>
I got the idea from http://www.vatoelvis.com/135g.php.  He uses it for cichlids, but I like the idea.  Maybe it would help with circulation at least?
<Maybe>
Well, as usual, I'm up at 3:00 a.m., searching the site, and the rest of the web, for anything new I have not seen yet.  Thanks for the reply whenever you get the time.  The site is wonderful, and I'm looking forward to some new books from you guys.                    Thanks, Mike
<Keep reading and keeping good notes Mike... you'll do fine. Bob Fenner>

135G FOWLR follow-up, cutting glass, overflows, LR over the Net, plumbing and WWM pix
Thank you for the reply Bob, I have just a few more questions and then I should be good at least until I get this thing set up.  I talked to a bunch of glass shops in the area, and they all said they would drill the sides, but no one will touch the tempered bottom (can't say I blame em)  With that, they also told me they cannot guarantee the sides will not break while drilling, but they will do it.  That worries me.  If it would happen to anyone, it would happen to me (I know Murphy very well)  So that leads me to overflow boxes, which also worry me.
<I'm more worried about the latter than the former in terms of potential for trouble>
But then I stumbled onto Lifereef.com, telling me that he hasn't had one malfunction in fifteen years.
<Wow! Well, maybe "he" hasn't... but how about their customers?>
I value your opinion very much and was wondering which route would you take?  
<In almost all scenarios to have the tank pre-drilled if possible before assembly, or drilled after...>
Actually, in your experience, are these custom glass places known for busting even annealed walls, or are they just covering there butts?
<Methinks the latter>
Secondly, I was planning on Caribbean rock for Dr. F&S, and then I found a listing on eBay, Item number: 4381101282, can you please take a look and tell me if this stuff is any good?  
<Mmm, did so... out of Ft. Lauderdale...>
I emailed them and asked about size pieces and they said to just let em know what I'm looking for.  Too good to be true?
<... do you want Caribbean, Florida rock? The South Pacific sources are better for general purposes... cheaper per volume, function>
Finally, please don't laugh, but in your last reply, you mentioned nitrate bottle necking.  I don't understand what that means.  Can you please explain it to me?  Thank you.
<Sure... by "driving" the forward reaction/s of nitrification... lots of aerobic space, oxygenated water, water flow... nitrate tends to accumulate in high/er concentrations... the means, mechanisms for nitrate conversion into other matter are impeded... and hence "bottle necking" (backing up in the reaction series) occurs>
P.S.  I would like to send a couple of pics of my DIY wet/dry, but I don't know what you mean when you talk about file size.
<Kilobytes, megabytes... we prefer a few hundred Kbytes size maximum... jpegs, bmps preferably>
  Oh yeah, that reminds me, if I have only one 8" baffle right after the bio ball chamber, will the other side of the baffle remain at a 8" depth, even though the bulkhead for the pump is only about 2" high?  Thanks again, I love you guys.              
Mike
<If your water flow is not too fast and I understand what you mean here, yes. Bob Fenner>

Bulkhead Recommendations
Hello there crew,
<Is it, could it be... Aquaman!>
I need your help big time. I'm in the process of setting up a 450g aquarium. The plans have already been given to the manufacture 5 days ago. I planned on have 6000gph circulation. The drains consist of (2) 2" bulkheads and the returns are (4) 3/4" bulkheads,
<Uhh, not through these fittings>
after reading info on wet web media I'm feeling that a need to increase the number of my drain as well as my return bulkheads. Please recommend what size drain and returns I should have and how many.
<Mmm, I'd increase both the number and size/diameter of through-puts here... at least two four inch drains, six two inch returns...>
The tank will have a center overflow for the drains and the returns are placed on the top of the aquarium towards the rear wall. I will need to quickly call the manufacture to make the adjustment.
<Mmm, a bunch more to consider here than you are asking... I wish we had talked over your plumbing/filtration configuration altogether. Please assure me you've read through our (WWM) articles and FAQs files on these subjects... Bob Fenner> 

Removing/Installing new overflow
Hello Anthony, hope all is good out there.
<Antoine's out>
I have a custom 54"x30"x24" starfire reef tank that has been up and running for about 3 months. It has 3" of Southdown sand (that is very alive right now) about 190 lbs of Marshall Island live rock. I notice that the rock and sand is super full of life, pods running around everywhere. I'm cycled by now, test kits show about 15 on my nitrates. I even moved a couple frogspawn and torch frags from my 90 gallon upstairs into it to see how they would take. I want to make the complete transfer of my corals and fish in a month or so. Well I got this nice deep tank (30") and with the internal glass overflow it loses the effect.
<Loses...? The effect of depth?>
The overflow comes out about 8" , and looking at where the bulkheads are I figure I could cut out and replace it with about a piece that would only come out 4"
<Sorry... this isn't clear to me>
It is really bugging me , and I'm serious about doing it. I didn't notice it till the rock was in there. Well I have all this live sand and don't' want it to die off. I do have a 180 in wall tank that I'm also going to be setting up as a FOWLR, so I was thinking I could fill that and put the live rock in that tank while I'm working on the reef overflow. But what about the live sand? Should I remove that while the silicone is curing or will it be ok?
<I would leave the LS in place... the day to cure will be less harmful than moving it>
Also have any of you ever removed an internal glass overflow only to silicone in another one?
<Yes>
If you know what the construction of a starfire tank looks like that might help, but it looks like there is a bottom piece of like 3/4 glass that is for the bottom piece, and then all the sides are sitting on top , siliconed in. I don't' know if that helps any, but I guess I'm concerned how dangerous it is to be cutting out this overflow, mostly when I get near the bottom and silicone seal.
It is a center overflow BTW.
<The silicone seal of the overflow is not part of the structure of the tank itself... as long as you don't cut into the tank seals... Bob Fenner>

Re: Removing/Installing new overflow
Thanks Bob. Sorry if I confused you. What I basically want to do is remove the center overflow and install another smaller one in its place. The one that is in there now is way too big, its taking up lots of valuable room. And yes its takes away from the depth effect of the tank, this thing is almost 30" long, and the tank is 54" long, so you see why I want to do it.
<Yes>
Would it be a bad thing to remove my sand and put it in really wide/long/shallow Rubbermaid containers , with just a couple inches of water to cover it ?
<Nope... should work out fine... just more work>
I have 3 of these storage bins that would hold all the sand, and I would only have a few inches of sand in each , so that way it won't starve for oxygen. What do you think of that? Versus leaving it in... Cause if I leave it in won't it have die off ? Also what is the minimum time for the silicone to be in there before I put the water back in ? Thanks Bob.
<Some small amount of die-off to be expected in either case... but acceptable. Bob Fenner>

Overflows on corner tanks
Hi Guys!
I am considering ordering an 80 gallon triangle shaped corner tank from glasscages.com and I am concerned about the overflows for a reef set-up. I know that two overflows are better than one because of the possibility of clogging. Because of the triangular configuration, it is really only practical to have one overflow at the back corner of the aquarium. Is this safe, and if not, what options do you suggest? Should I use both holes in the overflow for output to the sump and have my tank returns come through the top? Also, because they are a small company, there is not a ton of info about their product out there. What do you know about their build quality? Thanks in advance!
Joel Schwartz
>>>Hey Joel,
First of all, no issues at all with one overflow, put those concerns out of your head. Two overflows are only better than one on a large tank where they are needed because of flow rate, it's NOT a clogging issue. I had a 92 corner tank for several years myself.
Secondly, I wouldn't trust corner tanks from anyone but All-Glass or Oceanic.
Cheers
Jim<<<

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>

External overflows 4/4/05
Hey guys, I've asked this question on your forum twice and received two different answers, so I thought I would ask a third time! I'll then go with the majority!! Here's my problem: I bought an undrilled 155 gallon tank (second hand) with no overflow system. Unfortunately, I also inherited some fish Therefore, the tank is up and running with just live rock and a hang on skimmer. 
I am planning on adding a 56 gallon sump underneath and currently looking at CPR external overflows. I have a Mag 24 pump (return line 1") which after head pressure will provide a flow rate of about 1800-1900GPH. I'm going with two overflow boxes but here comes the confusion. Should the combined overflow rate match the pump rate or should it be slightly more in case one box gets clogged? I've heard both answers. Here are my options
1. 1 CPR 1400GPH which has 2-1" bulkheads each which is about 2800GPH with 4-1" bulkheads total or
2. 1 CPR 1600GPH box with 1-1.5" bulkhead and 1 CPR 800GPH box with 1-1"inch which is 2400GPH?
<Let me really confuse you.... I would suggest that your overflows be able to handle slightly more flow than you expect to run through them, but not much. Extra capacity is nice in case of partial clogging, but if the flow through the devices is too slow, air can accumulate and break the siphon. That said, I would choose the option that gives you 2400GPH. In an ideal world, I would suggest setting up temporary quarters for the fish and drilling the tank.>
My feeling is to go with the 2-1400CPR overflows. If I go with these, then all I have to do is mark the max water level in the sump to prevent over-flooding in case of a power outage. If I assume that this is what I'll go for, will the overflow boxes make too much noise? Should, or can I add a Durso standpipe? Any help would be appreciated, thanks again. Nilesh 
<Noise may be an issue, and "Durso" standpipes might help... if you can fit them into the overflows. There are other designs that accomplish the same thing as the Durso, but concentrically instead of with elbows. One of these may fit better. Good luck! AdamC.> 

External overflows part 2 4/6/05
Hey Guys, Boy do I want to do the right thing!! Well...I just found another overflow system called LifeReef overflows which swears that their overflows don't have problems like the CPR systems like siphon breaks and flooding problems. Have any of you used this system before? Is it true that this system is the answer to all of us who have not drilled their tank or is this a myth? 
<LifeReef has a top notch reputation (many consider them to be the best by a wide margin), but no overflow system is 100% safe from losing siphon or clogging. Good maintenance will further reduce the risk of problems. Give the hassle of tearing down the tank, a well maintained LifeReef overflow is probably a good option.>
I've realized in retrospect that I should of drilled my tank...if I decide to drill and empty my tank, where should I have it drilled, on the bottom or on the side? What diameter should I have done? Thanks again folks for your continual support... Nilesh 
<This depends on your exact situation, but I almost always prefer drilling a wall rather than the bottom. If a bulkhead fitting in the bottom of the tank leaks, all of the water could come out. On the wall (esp. just below the water line), it can only drain to the bottom of the bulkhead. Also, there is far more stress on the bottom of the tank, so this is where I would least like to weaken it. The size and number of holes depends on how much flow you want. A 1.5" drain will handle up to about 750gph. A 1" drain will handle about half of that. (rough estimates). If you do have the tank drilled, estimate very generously. It would be quite a hassle to find that you didn't have enough drain capacity! Best Regards. AdamC.>

External Overflows part 2 4/12/05
Well.. I had a chance to speak to the dude ( I don't know his name) over at LifeReef and it looks good.  The design looks rather simple, do you think that with proper info from the net...that someone who is sort of handy can make it...or should I bother and just buy them from LifeReef? 
<Working with Acrylic isn't that hard, but does require a good table saw, a router (preferably with a table) and some basic wood-working type skills.  If you are strongly inclined to do it yourself, it certainly can be done, but most folks find that the small cost savings isn't worth their hassle.  There is lots of DIY info on the net.>
As to drilling my tank, I'm going to find out what's involved from my LFS in my area. they just started to drill tanks for customers.  Thanks again for the info. Nilesh 
<My LFS charges $15 per hole.  A very cheap hole saw costs about $45.  So, if you need three holes, you break even.  Some stores will replace the tank if it breaks but most won't.  Be sure to find out and give due consideration.  Best Regards.  Adam>

Flow the Flow, Goin' with the Overflow
Hi, I am starting up a 75 reef tank. Your site has helped me a lot with most of my decisions. And I thank you for that. My question is, I am trying to get about 1300-1400 gph. I am trying to stay away from powerheads. I am going to drill my glass aquarium and I have settled on going with 3-4 1.5" overflows. After reading on your site that acrylic overflow boxes will not work on glass, I will now have to go with glass. The only thing is will I need to put the teeth on the top of the glass or will I be able to just leave it straight across? What I plan on doing is make the overflow stretch almost all the way across the back of the tank. 
Thanks for trying to understand my question. 
<Adam, that sounds like a pain. Why not just use the 1.5 bulkheads with a threaded strainer instead? Drs Foster and Smith sell these strainers in the 1.5 inch model for 7.00 each. James (Salty Dog)>

Flow the Flow Goin' with the Overflow - II
Now wouldn't that mean that I would have to put the holes at the top and then the water level would not be all the way to the top..? I am confused on what I should do then. Thanks.
<Yes, they will be at the top. The water level should be very close to the top. A glass company in your area could tell you a safe distance from the top that the holes could be placed. 
<James (Salty Dog)>

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!>

- 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 -- > 

Bulkheads and gph flow
Does anyone know if bulkhead flow rates are effected by where the bulkheads are located? e.g. upper rear wall of tank vs. at the bottom of an interior tank overflow box or some other set-up. 
< Mike, it really doesn't matter where the bulkheads are located. What reduces the flow rate is the length of tubing from the bulkhead to the destination and the use of elbows and forty-fives. James (Salty Dog)><<Mmm, actually... does matter... the further up, less depth of water, the slower the exit rate... RMF>>

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> 

Circulation Problems in a Reef Tank, Needs to Visit Conjunction/Punctuation Junction, too
I am having a problem balancing the water flow [going] from [the] main tank to sump, [then] from sump to refuge [that is] above main tank, and [then back] from sump to main.  I have a 58 gallon tank.
<Oh oh...>
I drilled the back glass. I have 2-1" bulkheads about 4" up from bottom of tank in the center for drains.
<Where?...!>
I also have 2 -1" bulkheads drilled on the ends of the back glass. 1-about 4" from top of tank and the other about 6" up from the bottom of tank on both sides.
<?!>
I have a 5 gallon refuge which sits right at the top of the tank. On the refuge I have a 3/4 bulkhead for water return from sump. Then [I have] a 1" bulkhead for drain into main tank. I have a Euro- fill 180 30 gallon sump that set[s] under main tank. Inside main tank I have an overflow box 19" tall by 8' across 6" from front to back covering the 2 1' bulkheads. I have two Durso stand pipes connected to the 1" drains, going with 1 "1/4 pipe for the stand pipes. In the sump I have an ASM G1-X skimmer. For return pumps I have 2 Rio Hyper Flow 14 HF power heads; these pumps are rated at 840
gal [gph] at 1', 660 [gph] at 4'. 
I have a 3/4 PVC pipe running up to the two discharges into main tank. The other pump is hard plumbed to the 3/4
bulkhead in [the] refuge. I also have a standpipe in refuge to drain back into main with a baffle where the discharge comes from sump. I tried this, but the force from the pump was really strong, causing a lot of bubbles in refuge and main tank, a lot of micro bubbles in main tank. Over all circulation was good, levels stayed even in all tanks, just a lot of micro bubbles. 
I tried to split the return from pump in sump to refuge and have 1 discharge go to refuge, 1 to main tank, but because discharge is higher on refuge than [the] 1 going directly to main tank that water would go to [the] lowest discharge and would not then go to refuge also. I then tried using valves to regulate water flow between the 2 discharges, but when I did this my overflow box began the flushing effect, [the] system would not balance out. Still had micro bubbles in main tank. Went back to 1 discharge to refuge, cut the flow back with valve, still had flushing with drains plus strain on pump. [I] did see a reduction in micro bubbles in main tank. I tried using 1 pump from sump, micro bubbles almost gone but barely have any overflow, not sure if this is enough circulation for corals hard and soft. 
For the 2 bulkheads on each side of [the] drains I made a close[d] loop on each one these, have a Mag 9.5 hook[ed] to a SCWD - one for surface, one SCWD for lower jet bulkheads. I do not know how to get rid of the micro bubbles [and] keep the same flow with the 2 Rio pumps, or if I need to for circulation [and] supply the refuge [to] keep it balanced with out the flushing and micro bubbles. I added a another baffle in sump right after [the] drain, before [the] skimmer, with 2 baffles after skimmer.  I really did not want to use sponges or filter socks. Any Help would be greatly thankful.
Thanks Jeff.
<Well, you have two issues... the circulation can be fixed only by re-drilling larger through-puts... unless you want to greatly reduce water flow... I would NOT have holes drilled near the bottom of tanks... as the consequences of power outage or pump failure from below will prove disastrous... Therefore I would silicone covers over these... The bubbles can be addressed by a few means... likely the best for you here is the use of Dacron "socks" over the discharge lines (below)... and baffles to provide air-free water to your pumps. Bob Fenner> 

AGA Overflows
I have been reading a lot about the shortcomings of the standard overflows that come with certain Aquariums. I have a 90 gallon AGA and was wondering if it makes sense to somehow convert the ¾ inch return line to another drain to increase flow and use a closed loop type of return instead.
Thanks,
John
<Does make sense... either to A) use the current small lines for a closed-loop recirculation system (in place of submersed pump/s, powerheads), B) Re-drill over these holes to much larger... or C) do A and drill new holes... Bob Fenner> 

125 plumbing
Hello to all.
I will soon be plumbing my 125 RR AGA and have a question. The tank has the standard 2 overflows w/ 1" and .75" bulkheads in each overflow. I am planning on using both 1" and 1 - .75" bulkheads for the drains to the sump. I will use valves to adjust the flow to the sump. 
<Why would you want to do this? No need for it.> 
Then use the other .75" bulkhead for the return. My return pump is a Mag 18 and will be plumbed to a manifold running along the top back of the tank feeding 3 outlets. Does this sound reasonable? 
<I would put a valve on the pump in the event the pump puts more water into the tank than the drains can provide.> James (Salty Dog)> 

Using two siphons and two overflows together?
Hello and thank you for your help. I have a 75 gallon reef tank that is undrilled which overflows into 30 gallon sump using a single tube gravity overflow box. The sump contains my EuroReef skimmer and a DSB. I have a 40 gallon refugium built and I want to add it to my set up. Would it be possible to use a dual overflow box that has two hoses, one to the sump and one to the refugium? I can see that balancing the flow rates may be a problem, or not, but have you ever heard of anyone doing this. Is it possible? 
< Yes, not a problem. I'd still make sure that each item can hold the overflow amount. Also, you may want to use two smaller pumps, instead of just adding another pump. Try it out and see what happens, but yes, it will work. ><<... An exceedingly poor idea... What happens if one pump delivers more water back to an it's "side" that has an occluded overflow? Will the other sump/refugium "hold" the excess volume? Will the tank itself overflow? I would NOT do this unless you fit an equalizer line between the two reservoirs underneath, and these were about the same "height" and they were tested to accommodate volume at rest and under power. RMF>>
Thanks. Chris
< Blundell > 

Refugium and sump
Hello
<Hi Chris, Justin (Jager) here>
...and thank you for your help.
<no problem tis what we are here for>
I have a 75 gallon reef tank that is undrilled which overflows into 30 gallon sump using a single tube gravity overflow box.
<Yes very familiar with those, I use two myself.> 
The sump contains my EuroReef skimmer and a DSB. I have a 40 gallon refugium built and I want to add it to my setup. Would it be possible to use a dual overflow box that has two hoses, one to the sump and one to the refugium?
<Yes, but you must drill both tanks or overflow one into the other to avoid flooding.> 
I can see that balancing the flow rates may be a problem,
<You won't ever get it right and keep it right> 
or not, but have you ever heard of anyone doing this?
<Yes, but their basement flooded with a lot of water.> 
Is it possible?
Thanks. Chris
<Well it is a lot easier, safer, and cheaper to get the 40 gallon and the thirty gallon drilled and run a connecting tube between them so that the water runs into one tank then when that one gets to the drilled connector, it flows into the next where the pump is and then returns to the tank, running a dual hose overflow box is highly difficult without this connector, and I have only seen it work once. and only until one pump wore out a bit and then it overflowed. it lasted all of 15minutes. The only safe way to do it is to have the sump and refugium connected so that if one gets more flow it will not matter as they balance each other out. My personal tank with a sump and refugium is set up with two overflow boxes and two separate hoses but does what you want to. Water gets pulled from both sides of the tank and then both hoses flow into the sump(1 for the wet/dry and one raw for the skimmer and DSB) which then fills into the PVC connector that was drilled into the side and then that falls into the refugium, this allows both tanks to stay at a predefined level using PVC pieces to change the level the water is collected at in the sump, and it allows for an emergency in case the pumps fail or the electricity shuts off as both tanks can absorb the extra water from the main tank. If one of your tanks is higher than your other then you can use an overflow box on the higher one to drain into the lower one but it is safer and cheaper to get them drilled by a professional, such as a glass supply or glass contractor as they have the correct drills and other tools. Good luck on this.  Justin (Jager) >

- Tank Modifications -
Good evening/morning folks!
<Morning here...>
Have a quick one for you. 
<Promise?> 
I am buying a 200 GAL Glass tank with corner overflows. Unfortunately, as we all know, the pre-drilled overflows are too small (1" Overflow (2X) and 3/4" Return (2X)) drilled in the bottom corners in an overflow box.  I was wondering if it would be possible/feasible/advisable to cut a piece of glass to size, silicone the heck out of it and cover the holes and re-drill larger holes in the back wall at the water line.  Do you think this would hold? 
<Yes.> 
Or is it a good place for a leak to form? 
<Should work fine... method has been used to repair tanks of all types. Don't be stingy with the silicone.>
Was thinking about drilling (2X) 2" holes for Overflow for corner boxes and (2X) 1.5" holes for the return in the center back (am planning on also adding a manifold around the perimeter for extra flow/turbulence).  As always, you folks are the best! Don't know what we'd do without you!
Tom (The Tool Man)
<Cheers, J -- >