Overflow and return pump

[theMeat]

The amount the pump returns to tank determines the amount that falls back to sump via gravity.
look at flow chart with head height figured in to get an estimate of how many gph you will get.

 

[theMeat]

You could use a calculator to figure in every elbow and whatnot to more precisely determine your actual gph, but it’s still a guestemate. Could use a flow meter or simply time how much falls into bucket then use math to calculate.
IMO use the flow chart, don’t go over max your drain can handle and good

 

[Silent]

Add pump set at max flow
If water is raising in the overflow too high, reduce flow until it stays steady and is not increasing.
Easy as that.

 

[MichaelReefer]

The drain pipe needs to go directly into the filter sock, at least that's the way I used to do it

Edit again


Looking at a BRS video, the can you lower the filter sock?

Not always, my Reefer 250 doesn't go straight in. It drops into a spot like his and then overflows into the socks.

 

[LadyTang2]

When looking at max flow and max head, is the max flow what it would be at no head or at max head?

Say a pump did 2000 maxgph and says max head is 5 feet. does it pump 2000gph if it does not go up at all?

 

[Silent]

2000 would be zero head and 5 feet would be 0 flow or too much back pressure on the pump causing premature failure.