sumps using hang on 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

[bsyoun]

A second overflow box would provide extra insurance, in case the siphon breaks on the other box, but I don't think this is very common if the overflow is designed/set-up properly.

If the noise from your overflow gets too loud, you can set up a Durso standpipe (http://www.dursostandpipes.com/).

[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.