Is it possible to design and build a leak proof sump?

[tjtax]

I want to build a DIY sump but my fear is creating something that will inevitably overflow and flood my living room. Is it possible to design a sump that will not overflow ? I have a 40 gallon AIO tank but I want more space to have a refugium and a better spot for my protein skimmer. I've purchased a HOB syphon and a small return pump but I'm still trying to figure out the best design. I picked up a 20 gallon (standard) tank at PetCo's 50% off sale. I'm looking for any thoughts and suggestions.

 

[RedoubtReef]

I've never had my sump leak. When you design it, you need enough volume to prevent overflow when the return pump is off. In this case you will be running 2 'return' pumps? One in the AIO and one from the fuge back to the tank, right? What kind of AIO tank do you have?

 

[Sisterlimonpot]

Short answer, of course.

You just have to plan out your sump design so that when power is lost, the water that drains from the main tank can be captured in the sump.

This is a concept that most sump builders understand, and if you're making your own, you just have to do the math and make sure that the sump is large enough.

 

[mues]

Using a 20 gal sump on a 40 gallon tank, I would guess it would be fairly difficult to flood with the typical reasons you're thinking i.e. power failure to return pump... Given that you won't fill the sump all the way to the top, just set your baffles so that the normal operating is around 10 gallons or so... I'd find it hard to believe that you'd get 1/4 of your tank back through siphon on the return.

Obviously drain size, return pump flow and other factors are involved.... and ATOs fail if you plan to implement one... but there are certainly safe ways to set that up. I have a 60 gallon sump for a 150 gallon display and get nowhere close to the top of the sump when unplugging the return.

 

[C_AWOL]

Calculate whatever the backflow of your display is and size the sump accordingly to handle more than what the gallon amount is.
Not sure how you're going to do your overflow from that 40 aio to a sump but if we assume it drains down 5" (likely less than this) then using LxWxH/231 (going to do this with a regular 40) it will back siphon ~13.25 gal.
That means that whatever sump you use needs to hold that amount if the pump dies/power goes out on top of whatever water (based on desired water height) is already in said sump.

 

[Boehmtown]

If it's feasible , you can drill a bulkhead in your sump that goes to a sewer drain. Just make it slightly above your sump level when it's off. That way you can just add fresh water to your tank and your old water will just overflow out of this bulkhead for water changes

 

[reefadam]

The only thing I haven’t seen mentioned is installing a check valve on the return line, (I still believe in having capacity should the check fail). During a power failure the water will siphon drain to the lowest point, bottom of overflow teeth or return nozzle, and whichever is lowest in the tank. The return line can siphon a ton of water depending on position. (A return “break” can also be helpful, essentially a small hole drilled in the return below the display water line to break siphon).
You can determine the volumes of water using the formula: length x width x height divided by 231= volume in gallons.
Use this to determine operating heights and sump capacity etc.
also, I always opt for the largest footprint sump I can fit in the desired space for this reason.

 

[jda]

Check valves get hard, brittle and fail over time. IMO, they are a waste of money. Flapper valve is better, but still need replaced in intervals.

Short pipe on your return means less water to back siphon. Anti siphon holes work for me. I also just made a larger sump that I ever needed... standard 29g fits under a 40g breeder stand, for example.