I have a Pentair Clean and Clear Plus 420 with 4 Cartridges. I had the pool built in 2008 and have had the same cartridges since. I have cleaned them often and once with TFP. At what point should I replace them? There are no tears but they look discolored (yellowish). I recently cleaned and then two weeks later I noticed an Alarm message on my pool pump indicating the filter is blocked. I checked and no tears and no blockage so I reset the Alarm message.
TA = 70