Sump for 36 gallon fresh?

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Aquarium Advice Newbie
Mar 2, 2024
Hello! I just joined to get some advice for my UNS 75p. I bought it secondhand with two holes already drained- 2.25 and 1.25 in diameter. I have no idea how to sump a tank! Or even if I should even use a sump! I know I would like to avoid an overflow if possible but I don't even know if that's feasible

Here's what I have so far with the sump idea:

(Please excuse my handwriting)

Thank you in advance!
The plus side to using sumps is that you are adding water volume and water volume lengthens the time you have to catch any potential issues that are developing. They are also a good place to hide your mechanical filtering and heating from sight inside the main tank. Sumps can add extra oxygenation to the water as well.

The downside of using sumps is that you will hear some water flow going through the pipes and into the sump itself. They are all based on overflow ( whether it's a separate box or into a drain pipe that is in the tank ). The key is to match your pump's water flow with the flow capacity of the drain and fill lines. Too little water flow in the return and your pump could have issues. Too much water flow in your return line and your main tank can flood and your sump can drain. Everything needs to be balanced carefully to avoid floods and overfills.

The question is never whether you need a sump. No tank needs a sump. They are an extra piece of machinery that has some benefits that can outweigh their minuses. In your situation, if you choose not to use a sump, you can get bulkhead fittings with a threaded female end and you can just use a plug to keep the water from going out the holes OR you can just silicone an appropriate piece of glass over the holes to keep any water from coming out the holes.

So the choice is yours. (y)
Thanks for the reply! I'm definitely leaning toward the sump option now since I would like to avoid having any visible equipment in the tank for aesthetics.

How loud would you say the sump drain is vs a canister filter? I'm keeping this tank in my bedroom. Also, how do I figure out the flow capacity of my pipes? I know in general that with a gravitational pull a 1" PVC can do 600GHP, but how does that change with an overflow or a ball-and-socket valve?
The big advantage of the sump over a canister is that you can clean sump things without turning off the filter. You can't do that with a canister ( unless you want a REALLY wet floor. :lol: ;) ) The downside is they are going to be noisier because you want the splashing to oxygenate the water. You can muffle the sound somewhat by making a spray bar over just an open ended pipe but you will not make it totally silent. It does help if you have a a stand with a cabinet style base so that you can close the doors.

This a link to a flow chart for different sizes of PVC pipe:
Keep in mind that the flow rate is based on unobstructed flow so for example, if you have a 2" pipe that connects to a 1" bulkhead fitting so it needs to connect to a 1" pipe to go through the hole, you have to figure the flow rate based on 1" pipe not the 2". That also applies to any reduction in pipe size from the hole to the sump. So the flow rate always applies to the smallest pipe diameter in the line the flow goes through.

Regarding your drawing, I would reverse the use of the pipes. Make the large pipe the drain line and the smaller one the fill line. There's no need to use a ball valve on a drain line unless you are diverting water into different areas. ( more on this next paragraph.)

Depending on the size of the pump you eventually get, up may have more flow than your pipe really should have. It's never a good idea to restrict flow to or from the pump as it burns up the motor faster so in the pump line, place a Tee in the line with a valve past the Tee going to the tank and an open ended pipe from the Tee into another section of the sump away from the pump. As you adjust the valve so that the flow into the tank is not too strong, the excess water will naturally go to the pipe off the Tee with no valve and just go back into the sump. (y)
So this is how I set up all my tanks and businesses that used a sump. (y) (y)

Hope it helps. (y)
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