[likemike99]

I have a 125 FOWLR with 4 emperor 400 HOB filters . I recently made a 30gal into a sump. I connected everything but I am having trouble equaling the overflow and the return flow. How low should the overflow be below the water line? My thought was to put it about 1/2 inch below this way evaporation won't effect it frequently and more water won't effect it since it is already siphoning at max. both the siphon and pump (whiser 4000) are rated at 100gal/hr. does this setup sound right?

[pogodzib]

When the return pump is off, the bottom of the overflow weir should be at the waterline and the sump will have its maximum amount of water in it that you feel safe with having. When the return pump is running, the water level in the main tank will raise (and sump will lower) until the water that flows through the overflow weir and piping at the same rate as the return line.

[likemike99]

never thought of that . good way to avoid floods. thanks