Is there a reason to get only OEM replacement cartridges? I purchased non-Jandy cartridges last year (manufactured by Pleatco). They seem to get "dirty" faster and result in quicker increases in psi. I found that my old Unicel cartridges could take a greater beating than the Pleatco ones while keeping the pressure in the preferred range. In addition, it seems like they did a slightly better job of catching the small junk that often goes through the filter and shoots back out the returns when I am running with the Pleatco cartridges. I have noticed that the Unicel cartridges feel more substantial. They are heavier. And the center is bi-sected, whereas the center of the Pleatco cartridges are completely hollow.