im using a Quiet One Model 4000 it pumps a little over 1000gph, i tried a 500gph pump and it just wasnt enpugh pressure for the 7 sprayers i had at the time. now i have 8 sprayers, you'll see why when i get some pics up(was a little stoned during construction). im using 6 320s sprayers and 2 180s and it works great.