overflow problem

[gord 23]

I want to put in a sump using an overflow box for my 75 gal tank. If the return pump quits will I end up with a lot of water on the floor?

[mcgyvr]

Originally Posted by gord 23

I want to put in a sump using an overflow box for my 75 gal tank. If the return pump quits will I end up with a lot of water on the floor?

Potentially yes..

When a return pump dies or power is lost AND the top end of the return pipe is below water then water will start to flow backwards down the return pipe because a siphon is started (back siphon)..
That siphon will continue to flow until air is introduced into the line thus breaking the siphon..

The ways to introduce air are
#1-Anti-siphon holes which are holes drilled in the return pipe at/just below the normal surface of the water in the display tank
#2-Keeping the outlet of the return pipe in the display tank at or near the surface of the water
#3-A check valve in the return piping (this check valve is prone to fail and not recommended)
#4-Some other siphon break system..

You should leave some room in your sump for the overflow (back siphon) amount of water that will drain back..

If you take care of that then No you won't have a flood.

[nereefpat]

The short answer is no, not if set up properly.

Good advice above. ^^

[Yin_Yang247]

Make sure your sump has proper sized baffles so incase your overflow fails then your main tank won't overfill and cause a flood. Baffle the return pump area in the sump to be very small and most sumps are built with small return pump area.