Hi, I am about to replace my Sta-Rite DE filter (torn grids, stuck backwash valve and I'm just sick of DE in general) w/ a Hayward cartridge filter. The filter that was recommended for my 13000 gallon pool has 120ft2of filtration area. The Sta-Rite it is replacing has 37ft2. Are cartridge filters rated differently than DE filters or was my previous filter woefully inadequate for my pool size?