Can anyone tell me if 8psi is normal for a cartridge filter system? I pulled both filters out last night and swapped them with ones I rinsed off. I haven't cleaned any of them in TSP yet, I was going to wait until after I'm done getting the pool clean to fully clean the filters. I just want to make sure that 8psi is ok. It doesn't seem to rise at all even when it gets dirty. The filter was filthy and it was still at 8psi.