I have a Northstar 2hp spd pump with 500lb sand filter, 2 1/2" piping, 4 returns, 2 main drains and skimmers, spa, and swimout. On high speed it moves alot of water. Pump pressure reads 20psi with everything open. 18x36 pool. I only run it on high for 1hr twice a day. The rest of the time it runs on low speed. Seems like to big a pump for your setup. Not very efficent, like putting a straw in the end of a garden hose.