I have 33000 gal inground pool starite system 3 sand filter with pentair 1 hp superflo pump I can not get any pressure on filter mode this is brand new filter Brand new sand and pump is only two years old. No air bubbles in pump. Is my pump too small? I have two skimmers 1 main drain I've closed off each one to try get better pressure it stays the same 0 and when I open air release valve air sucks in or water barley comes out