water flow?

[Joemama16341]

I am building an overflow and need to get a pump for the return. How do you figure out the flow of water through a given size of pipe so I can match my pump as close as possible to my overflow?

[RMPD109]

Your return pump will regulate the rate of the overflow. Most overflows are rated for 600gph but unless the return is providing that much it will automatically use what the pump is returning.

[Bearfan]

HERE is a good calculator to determine head loss.