Calculating head and proper filter pressure

[Water_man]

Ok, based upon that information here are a few estimates and I say estimates because we really don't know what is happening on the suction side but from the filter pressure I can get close. We can nail it spot on if you can actually measure the suction at the pump via the drain plug but you would need a vacuum guage for that.

Anyway, here is what I have:

With the single 1 1/2" line: ~40 GPM @ 50' of head
All lines open: ~48 gpm @ 44' of head

The filter can probably handle much more than that so I wouldn't worry too much about flow rates.

Let me know if you need anything else.

OK, I finally got my vacuum gauge from amazon on line (Sears and others don't carry it) and I also replaced my
older filter pressure gauge.
The filter pressure when all returns are open is 11 (old reading was 9) and the pump vaccum is 14 inch Hg, which means head of 41. You came up with 44. Good job, thanks!