Today I replaced my cartridge filter with a 22" radiant sand filter that takes 220 lbs of sand. I had to use my gauge from my other filter and it's reading 30- 35 psi so I back washed it and now it says 27 psi but from what I understand that is still too high? My pool is 12500 gal. It has a 1 1/2 hp pump and everything is working properly but the pressure makes me nervous. My pool was with out a filter for a month and it's not green but it's super cloudy and has a film and some stuff floating on top. You can't even see the bottom in the shallow end. What should I do... I put stabilizer/ clarifier, 5 lbs of shock and algae killer in it. Help!!!