My old pump was a 1.5 HP with an old Sta-Rite Swimquip DE Filter. When I switched I decided to go back with a 1-HP and a sand filter. I figured that since the filter was rated for ~60 gpm I was in good shape but now I'm finding out that I'm really at the upper level of flow for that filter and I have never really had consistent results. I'm strongly considering either going back to DE or up one size on my sand filter.