Is it time to replace my cartridges? Ive had my Pentair size 75 cartridge for my 9000 gallon fiberglass pool. Recently after cleaning them, the pressure I get when installing them is 10 psi. Within 5-10 hours, the pressure icnreases to about 20 psi. My pool is really not dirty; I have a feeling that the filter is clogged with either calcium (my calcium was on the higher end). I use the Taylor kit for measurement. I use the TFP method of using bleach only.
The cartridges are about 4-5 years old but living in the NE they are used only for about 5 months a year.
I clean them by placing them in a bin, add dishwasher detergent then let them soak for 24-48 hours. Then I rinse with garden hose cleaning until nothing but water comes out on the bottom.
The pool chemistry is all within order. Even the CYA is 40.
Should I replace them?
Any other advice will be appreciated.