sumps using hang on overflow

[King of the Sea]

If i bought a over flow box that was rated at 600 gph on a 100 gallon tank does the pump have to match the gph of the overflow exactly?

[GrimReefer]

600 gph is a maximum.

[pat]

you want your pump to be rated higher than you overflow box,you have to take in considaration of the head you will be putting on your pump.
HEAD means the hight the pump has to push the water up to reach the tank.In my opinion your better off with a pump rated for double your overflow.

[King of the Sea]

maximum 600 for what

[bsyoun]

I believe that 600 gph (gallons per hour) is the maximum rate the overflow can handle. As a result, if this was the only overflow that you had in your tank and you were pumping water at a rate greater than 600 gph from your sump to your tank, then you'd probably have a big mess on your hands.

[pat]

not if you add a ball valve

[bsyoun]

very true.

[King of the Sea]

think need two overflows?

[andsoitgoes]

I have a 600gph overflow being pushed back by a MJ 1200 to about 4' head - never a problem. The overflow will adjust to the speed of the return

[mark]

Should find a pump factoring in head loss that will match to your overflow or the flow you're aiming for (eg pump rating - head loss = overflow rating). Unless you have plans for teeing off the return for some other function (Ca reactor, phosban reactor or such) you're really just buying a bigger pump for nothing.

If planning on relying on the return pump for circulation only, 600 gph on a 100g not that much turn over. If the return pump is only to cycle water through the sump and have powerheads, streams or a closed loop for display, 600gph should be enough. Haven't played with hang on overflows but would imagine more you push through them, noisier they may be.

Should be using a ball valve and unions though to allow to remove pump for maintanence or repair if pump's to be external.