Just cleaned my CCP 420 for the first time since the pool was completed in December 2010. It was more work than I expected. It was hard/time consumming to clean the gunk from between the pleats.
The original pressure was 19 psi and before I cleaned it the reading was 26 psi. After soaking the cartridges in dishwashing detergent (but not one cup per 5 gallons--probably used 1/3 of that) overnight and thoroughly hosing them down (before and after the soak) the psi on restart is 22 psi. I can't imagine getting the cartridges any cleaner--unless I spend several hours cleaning them. Should I be concerned that the pressure did not return to the original startup pressure?