My tank is a 135 gallons 72" x 18.5" x 25". The overflows are 23" x 5" x 5" each side has 8 opening, each opening is 1/4" apart and they 1" deep cut. It drains into a 1" bulkhead. But to the bulkhead right now I have the Durso pipes at 1.5 PVC plumbing. From the overflow it goes back to a 1" pipe into the 29" sump.

How do I figure out how much water is going thru my overflows? 600gph, 800gph, 1000gph, I do not have any clue. Maybe once I figure that out I can figure out what kind of pump I need. :cry: :(

Thanks,
Carlos
The reef rookie