I normally clean out the DE cartridge once a month, and after cleaning the psi would be in normal range of 8-9. Lately, after I clean it, suprime and start pump, psi increases after 30-45 minutes.
Ininsoecyed cartrdige and they’re clean, however are 12 years old and may need replacements. One of the cartridges had a tiny Year and I found small broken piece when inspected.