If your current filter measures 26” in length with a 7” outer diameter and 3” open on both ends, this cartridge is likely a match. For quick confirmation, use the compatibility search tool above or verify that your system uses Pentair Clean & Clear Plus 420 or 520 (pre-1998).

Pool use, debris load, water conditions, and filter size all affect when a cartridge needs cleaning or replacement. This filter is designed for a 4-cartridge pool system. To support long-term filter performance, rinse and replace all 4 filters at the same time following the guidelines below as a practical baseline.

For best performance:

• Rinse: When filter pressure rises 8–10 PSI above clean baseline, about every 6–8 weeks during regular pool use
• Peak Season: Check every 5–6 weeks during heavy debris or high bather load
• Deep Clean: 1–2 times per year, typically mid-season and end-of-season

Signs it’s time to replace (typically after 3–5 pool seasons):

• Reduced flow even after deep cleaning
• Rising pressure that doesn’t improve after cleaning
• More frequent cleanings needed to maintain normal PSI
• Frayed, crushed, or flattened pleats
• Cracked or damaged end caps
• Loose, damaged, or broken bands
  

The media is treated with antimicrobial protection to help inhibit bacteria, mold, and mildew growth on the filter media, so the cartridge stays fresher between cleanings. (It doesn’t replace proper water chemistry or regular cleaning.) It also helps extend the life of the filter by reducing buildup.

Absolutely. The ProGrade™ pleated media is designed for repeated use. Simply rinse the pleats thoroughly with a garden hose, spraying between pleats to remove trapped debris. For deep cleaning, soak the cartridge in a cartridge filter cleaning solution, then rinse completely before reinstalling. Let it dry if your cleaner recommends it.

Yes. The CPF-1977 filter is certified to NSF/ANSI 50 standards, which means it’s been independently tested to meet strict benchmarks for material safety, filtration performance, and durability in pool systems. It’s a filter you can trust, backed by science and built for clarity.

It can. By capturing more debris and contaminants before they circulate, this filter helps maintain water balance longer, reducing the need for frequent chemical adjustments. Cleaner water also helps your sanitizer work more efficiently, so you use less overall.

DiamondCore™ Technology improves water flow and resists clogging, reducing strain on your pump and helping it run cooler, quieter, and longer.

Each cartridge features reinforced ProGrade™ pleated media, durable end caps, and a DiamondCore™ support structure engineered to withstand pressure, backflow, and repeated cleaning cycles without collapsing or cracking under strain.

Yes. This filter is compatible with Pentair Clean & Clear Plus 420 and 520 (pre-1998) CC420, CCP420 4-cartridge systems. Use the compatibility search tool above to confirm your fit before purchasing.

Clarus filters are built for performance, not shortcuts. We use premium ProGrade™ pleated media, a reinforced core built to hold shape under pressure, and antimicrobial-treated filtration media to help keep the cartridge fresher between cleanings. Translation: stronger flow, better debris capture, and durability you can actually feel so you spend less time swapping filters and more time enjoying clear water. And for extra peace of mind, Clarus filters are NSF/ANSI 50 certified, meaning they meet recognized industry standards for safety and performance in pool and spa filtration, so you can trust the filtration doing its job, day after day.