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FAQs about Overflows, Through Hulls, Related Plumbing 

Related Articles: Plumbing Marine Systems by Bob Fenner, Myth of the One Inch Beast (Why Relying on One Inch Overflows... or Overflow! Is foolhardy) by Scott Vallembois, Plumbing Return Manifolds, Refugiums

Related FAQs: Holes & Drilling 1, Holes & Drilling 2, Holes & Drilling 3, Holes & Drilling 4,  & FAQs on: Rationale/Use, Designs, Fittings, Sizing/Number/Placement, Tools & Processes Themselves, Troubleshooting/Repair... Marine Plumbing 1, Marine Plumbing 2, Marine Plumbing 3, Marine Plumbing 4, Marine Plumbing 5, Marine Plumbing 6, Marine Plumbing 7, Plumbing 8, Plumbing 9, Plumbing 10, Plumbing 11, Plumbing 12, Plumbing 13, Plumbing 14, Plumbing 15 Plumbing 16, Plumbing 17, Make Up Water Systems, Pumps, Aeration, Circulation, Sumps, RefugiumsGear Selection for Circulation, Pump Problems Fish-Only Marine Set-ups, Fish-Only Marine Systems 2, FOWLR/Fish and Invertebrate Systems, Reef Systems, Coldwater Systems, Small Systems, Large SystemsWater Changes Surge Devices

Sump Refugium Return Pump      5/6/16
Hello Wise Crew Members,
<More like wisenheimers>
I have decided to change out my Velocity Poseidon PS4 return pump that is externally mounted from my sump refugium for a EcoTech DC M1 pump. The inlet and outlet of the Poseidon pump is 1" however the Vectra DC M1 pump with the adapter pvc kit inlet is 1-1/2" and outlet is 1-1/4". How can I replace the bulkhead on the sump to accommodate the new pump with my aquarium active.
<I'd just bush all up; as with bushings; hopefully threaded (best) w/ Silastic as a bit of seating. Schedule 40 PVC will do here. I would NOT go through the trouble to re-drill the sump/refugium and up-size the bulkhead>
Should I turn off the ball valve ball valve between the pump and sump and just drain that section where the bulkhead is and re-drill for the new bulk head?
<Again; this would not be my preference>
The sump is 1/4" acrylic. I know that I would have to replace my braided hoses. Please see attached pics.
<Too many Megs... why don't folks follow our directions?>
Thanks Kindly,
<Welcome. Bob Fenner>

Fluctuating Sump Level; one inch drain line/s      11/9/14
Dear WetWebMedia,
Thank you so much for your service to the aquarium trade. I have successfully kept a reef tank for seven years. My original fish are still alive and thriving. I owe it to following the advice I've learned on this
I apologize in advance for my lack of physics knowledge. I also apologize for the lengthy email as I don't know what information is important. A couple months ago I moved and had my reef tank upgraded to a 120 gallon tank at the same time. It is a room divider tank and visible on three sides. The overflow is located on one side of the tank. It currently has one 1" drain
<Mmm; too small... needs to be... "over-sized"... at least 1.5 inch for this volume system, sump... in fact, two drain lines would be preferable to one... Oh, I see below...>
with a Durso, one 1" drain that is unused,
<I would use this drain as well>

and a 3/4 inch return. The return is rated at 1200 GPH. There have been problems from the start. The Durso appears to be tuned correctly with no flushing. To start, the drain line vibrated/shook and sounded like a dishwasher.
<Yes; overwhelmed... siphoning intermittently.... maddening noise wise>

We attempted to solve it by cutting the drain line shorter to allow it to hang straight down and just below the water level in the filter sock. The noise and shaking continued.
<Ah yes>
We then drilled a few holes in the line to allow air to escape. This greatly reduced the shaking and noise, but did not eliminate it.
<Won't do so... either have to slow the rate of flow down (by pumping less), OR adding another drain (of size), OR re-drilling the present drain line, fitting a larger through-put/bulkhead fitting and larger diameter
I have an auto top off unit in the sump/refugium that beeps if the water level rises above the sensor. At least once a day the water level in the sump rises and sets off the alarm. Tonight when it happened, I watched the sump water level go back down to below normal. I then noticed that the water level was unusually high (by a couple inches) in the overflow. The water level was higher, but not "flushing." It also seemed like the drain line was substantially quieter. I turned the pump off to check for an obstruction in the drain line, but couldn't see anything. When I turned the pump back on, the level in the overflow was back to normal, but the level in the sump was too high again. It makes me nervous having the water
level fluctuate like that.
<Ah yes>
Do you have a guess as to what the problem is?
<Indeed I do... very common w/ undersized plumbing as you have here... the system is oscillating twixt flow and siphoning down the one drain line... when the water is backed up in the upper tank, the sump is drained sufficiently to set off the auto top off alarm...>
I'm assuming the problems have something to do with the drain not being able to handle the return rate. Is that correct?
<Ah yes>
If so, would it help to utilize the extra 1" drain?
<I would employ it and hope it does so>
If so, is it ok to have two dursos in the same overflow?
I already inquired about making the drain holes bigger, but was told the holes were as large as they could be with there being three holes in the same small area.
<Yes; an engineering/design defect. There have been quite a few commercial systems... and custom with this mistake>
Thank you in advance for any help you can give me.
<I would first try using both one inch drains... IF this doesn't "do it", I'd slow down the rate of flow to/from the tank... and provide more flow INSIDE the main/display tank with submersible pumps (see WWM re); using the sump less... IF this doesn't satisfy, the present holes can be abandoned, a piece of material placed over them and the tank/drain area re-drilled, WITH one larger drain line (2" if it were up to me) and a one inch return. Bob Fenner>
Re: Fluctuating Sump Level     ‏            11/10/14

Thank you so much for your help! We opened the second drain line and added another Durso. So far so good! It looks like it is now draining properly. And the tank is so much quieter!
Thanks again, Michele
<Ahh; good news. Thank you for your report. Bob Fenner>

Overflow box... reading      6/26/13
Hello gang. I've scoured your sight <site> and have come up blank
 so I have another question for you fine folks. I have a 150 gallon FOWLR tank that has been up and running for 3-4 years that is doing very well.
Having said that, I've always wanted a little more "current" inside the tank. I've had some slight algae problems here and there, nothing of major significance, but have wondered if some increased water flow melt help alleviate that issue...especially since it's really been the only "issue" I've encountered thus far. Anyway, my thoughts surround drilling additional holes in the corner overflows that exist inside the tank. I've seen plenty of other overflows out there that have holes midway down the box in addition to the teeth along the top. In my case though there are only the teeth along the top. Would it be your suggestion to go ahead and drill some additional holes somewhere around "mid tank" on both of the overflow boxes or would you suggest something else?
<Depends... first: if you just want to increase circulation in the tank, I'd use pumps inside the tank itself (not outside)... Read here: http://www.wetwebmedia.com/marsetupindex2.htm
scroll down to the Circulation area and read>
 I would be certain to make sure and use a bit that drilled holes the same size as the one in the upper teeth, assuring that nothing in the tank would be able to squeeze through into the overflow. Thanks!
<Second; IF you have adjustable riser/s in your overflow box you might be able to drill the holes you have in mind; but you might need to drill out (enlarge) the through put/s to accommodate the flow. IF you don't have said adjustable risers, nor can retrofit them; drilling holes will ultimately be a disaster; when power or your outside recirculating pump/s fail, and the water drains down to the level of the holes, and overflows your sump (unless the outside plumbing, gear is pressurized, not a sump), and onto your floors. Bob Fenner>

Upgrading tank and corals losing color    11/23/12
Hi crew!  I've got a hodge podge of questions.  I'm upgrading from a 55 gallon (non drilled) with a 30 gal refugium to a 80 gallon drilled frag tank.  Since I'm going to need new substrate I've been reading the recommendations on WWM for reef tanks and believe Aragamax oolithic is recommended at a depth of 4". I do have a 4" DSB (oolithic) in the refugium and will use this refugium with the new tank.  My main goal for the substrate is for pH and alkalinity stability 1. Will it be beneficial to use the oolithic DSB in the DT?
<Yes; highly>
 2. How many pounds of sand will I need?
<Mmm, likely 150, perhaps a bit more... I'd look to buy in bulk>
 The new tank's footprint is 48 x 24.  I will be keeping my existing sand to seed the new sand. 
<Ah good. Then perhaps a bit less to buy>
Plumbing: Since I don't have experience with drilled tanks I've been researching hooking it up to plumbing. The new tank has 2 drilled holes in the corner.  I've read on WWM to have a back up drain in the event the first one fails (blocked, etc). I was thinking of doing this with the 2 existing drilled holes, even though the one is for the return, and hanging the existing return on the back of the tank. Any advice?
<Mmm, yes; to continue reading... for now... there are a few options, and you should be satisfied that you've personally investigated... Most all is gone over (and over) in WWM's archives/FAQs>
 Also, I've read on forums that the bulkheads that came with this tank (Deep Blue) are junk and need to be replaced.  Have you heard anything of the like?
<Mmm, a bit; they're a bit more flimsy... I'd rather use schedule 40 PVC than ABS... and two gaskets (one for in, out) and a smear of aquarium Silastic... again, gone over on WWM if you'd like more detail>
 Lastly, I've had problems with my corals losing color, even mushrooms.  In trying to rule out culprits I've tested the water for everything, except for elements like potassium,
<An upcoming topic in our interest>
etc, changed out bulbs (T5), use Rod's for feeding, and use Tropic Marin Reef Salt all to no avail. However, I was reading on WWM FAQs that it could be allelopathy. 
<Yes; quite common>
Could this be a reason for color fading?  I have Sarcophytons, Cnidarians,
<These are all Cnidarians; the phylum>
 Sinularias, Xenias and Zoanthids.  All are fully extended and seem pretty happy except for the color. I've written before about this and Mr. Fenner replied it could be the phosphates and nitrates being too low.
<Also prevalent in these days of (over) use of chemical filtrants. Chemo and Photo-synthates absolutely need some (measurable concentration) of both>
Any advice will be greatly appreciated.
Thank you crew!!  Jennifer
<Welcome Jen! Bob Fenner>

Best way to overflow a cichlid tank   3/26/12
Hi Team,
 After several hours of research, I am thoroughly confused about the best way to get water out of a cichlid tank into a sump because most overflows seem to be for marine systems so I would be grateful for any advice?
<... Ok>
Planning a 125G (54L X 24W X 24H) All male peacock/haps tank with a 30g sump and a 2217 (that I already have) for filtration.  I am assuming that such a tank will generate lots of waste and hence want two ways to filter.
What I am not clear about is how to get the water OUT of the tank given that most of the waste I am trying to remove is going to be at the bottom of the tank.  The tank is not ready yet so getting it drilled is not an issue except that the hole cannot be in the bottom (lateral wall holes are ok).  I am considering the following options (noise is not a problem as the tank will be in the balcony):
<All right>
1.  Regular corner overflow with weir and Durso (exiting out of side wall instead of bottom, will that work?).
 Will this be effective in sucking waste from the bottom?
<Mmm, no... there are no more practical ways to accomplish this than frequent vacuuming, water changes>
 Should I use UG jets with this?
<I would add circulation with such, yes>
2.  A DIY version of the Tunze 1076 wall overflow assuming I can build it:
http://www.tunze.com/fileadmin/images/product_database/1076_2.jpg  as this seems to both skim and suck
<Won't do the latter>
3. A simple DIY skimmerless overflow from pvc such as:
<Another possibility>
What would be the best option overall?
<The Durso... Please read here: http://www.wetwebmedia.com/thrhullsiz6f.htm
and the linked files above; particularly ScottV's articles. Bob Fenner>
Thanks in advance!
Re: Best way to overflow a cichlid tank    3/29/12

Thanks Bob!  I tried out the DIY pvc overflow (it worked!) and now understand why you recommend a 1.5inch tube at minimum (I tried 1 inch and found the siphon couldn't keep up with the return pump unless there is a large sump).
<Yeeikes! Don't rely on siphoning!>
It is wonderful having experts like you sharing wisdom for free:-)
<Welcome! BobF>

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