Drilling The Back Of A Tank For Overflow Drain?

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Fish Crazy
Aug 25, 2006
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will this work? if so, what should the drain pipe diameter be working against about 500gph return pump?

Remember, you can't have too much return diameter, and you may upgrade your return pump later, I'd go 1.5" (~3.8 CM) personally. Also you should consider making sure that none of the pipes are solidly vertical or horizontal to avoid the toilet affect, maybe even put some sponges in to reduce the splashing sound.
toilet affect?

is that a noise issue or something else?
yea it is the splash of water as it leaves the pipe work, and then hits it again at a faster speed. make what sounds like a leaking noise. bit like a water fall. if you have the space you should try to allow the water to run along the pipe work. a bit like as if it was a smooth running river. this should also allow more air out of the water and not get the gurgle effect.

hope that helps mate :)

Rob :good:
To combat noise you'll also need an external standpipe. Basically instead of having that right angle outside of the tank, have a T fitting there instead and a piece of pipe extending just a couple inches above the water level. Cap off the end of the T and drill a very small (1/16") hole in the top of it to allow air to get sucked into the drain pipe. Helps combat the gurgling sounds ;)
when i add a sump to the tank whats the best plan for plumbing and how big exit and return holes should i need.
I forget how big your tanks/pumps are, but you should be considering between 3/4" piping for a single 55g tank and go up to 1" for 75-90g tanks, and 1.5" for like a 120 or 125

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