Pool & Spa Filter Cartridges
One cartridge, five different part numbers depending on who printed the box. We cross-reference all of them — type any number printed on your old cartridge, land on the exact-fit replacement.
Type your cartridge number
Unicel, Pleatco, Filbur, Hayward CX/SPX, Pentair R or APCC — any of them works.
No number? Measure it — diameter × length × square feet works too in the size finder.
Three numbering systems, one cartridge
Enter by whichever you haveThe most-cited system in the US — the "C-series" numbers etched on the cartridge end cap. If your filter has a number molded into the plastic, it's usually this one.
373 numbers cross-referenced Browse Unicel-compatible → Pleatco PA## · PAP### · PWW##The OEM line most pool stores push (Pentair acquired the brand and raised MAP pricing 20–25%). Our replacements match the same specs without the premium.
PAM / PA / PAP / PWW families covered Browse Pleatco-compatible → Filbur FC-####The manufacturer-direct system — same physical cartridges, sold B2B without retail marketing. Often the cheapest reference point for the identical part.
FC series mapped to both systems above Browse Filbur-compatible →Unicel® and Pleatco® are registered trademarks of Pentair; Filbur® is a trademark of Filbur Manufacturing. ClearFit cartridges are independent compatible replacements — every listing states "replaces / compatible with", never an OEM claim.
The eight most-searched cartridges
Real fit data, not guessesRanked by real search volume from our cross-reference library — summer peaks push the top numbers 2–7× higher in season. All 480 numbers get the same treatment: full interchange chain, square footage, measured dimensions, 2- and 4-pack pricing.
Browse all 480 cartridges →The pool year, on one ribbon
Your cartridge's clock follows the season, not the calendarIt's peak season — your filter is working overtime
What this means for your cartridge: in peak season, rinse every 2–4 weeks and expect a shorter cycle — heavy bather load and sunscreen load the pleats fast. Closing orders spike late September: the cartridge you install at closing is the one that opens clean in spring.
Not sure your number is even right?
The Cross-Reference Lookup accepts fridge model numbers, HVAC sizes, RO system names and pool cartridge numbers — one tool, every category. Paste whatever's printed on the part or the appliance.