Maintaining a clean, efficient pool means keeping a close eye on your filtration system, and cartridge filters are common choices for homeowners because they’re easy to service and efficient at catching debris. One of the most frequent questions pool owners ask is “How often should I replace the cartridge?” There isn’t a one-size-fits-all answer, but knowing typical intervals and what affects cartridge life will help you make better decisions and avoid costly water problems.
Replacing a cartridge at the right time ensures good water clarity, lowers strain on your pump, and prevents contaminants from cycling back into the pool. The guidance below covers typical replacement timelines and the signs that tell you the cartridge has reached the end of its useful life.
When to Replace Your Cartridge Pool Filter
Most cartridge filters last roughly 3 to 5 years under normal residential use, but that estimate can shift depending on how often the pool runs, how dirty the environment is, and how well you maintain the cartridge. Lightly used pools in clean settings sometimes stretch to 5–6 years, while busy pools or those exposed to heavy pollen, leaves, or frequent swimmers may need new cartridges every 1–3 years. Manufacturer recommendations are a good baseline—check your filter’s manual for specific guidance.
Beyond a calendar-based schedule, replace the cartridge when cleaning and chemical treatments no longer restore good flow and clarity. A practical yardstick is pressure: note the pressure with a clean cartridge, and if the gauge reads 8–10 psi higher after cleaning and the water remains cloudy, replacement is warranted. Similarly, if you find yourself cleaning the cartridge every week just to keep the water acceptable, that’s a sign its filtering capacity has diminished.
You can extend cartridge life with routine care: rinse with a hose every 2–6 weeks depending on use, soak periodically in a cartridge cleaner to remove oils and scale, and make sure your pool chemistry stays balanced to prevent chemical damage. Winterize properly in cold climates, replace worn O-rings, and avoid running the pump if the cartridge is clogged—these practices reduce wear and delay replacement. Still, plan to budget for new cartridges as part of annual pool maintenance so you’re ready when performance drops.
Signs Your Cartridge Pool Filter Needs Replacing
Visible damage is the clearest signal: tears, crushed or flattened pleats, and broken end caps or core indicate the cartridge can no longer trap debris effectively and should be replaced immediately. Look for shredded material, holes, or pieces missing from the pleats when you remove and inspect the element. Physical deterioration is irreversible; cleaning won’t fix torn or collapsed pleats.
Performance-based signs are equally important. If you experience persistent cloudy water, algae outbreaks, or a reduced flow rate that doesn’t improve after a thorough cleaning and chemical treatment, the cartridge’s media is likely spent. Another mechanical indicator is a consistently high pressure reading on the filter that remains elevated after a proper cleaning—this means the pleats are fouled or clogged beyond recovery and the cartridge is restricting flow.
Other indicators include black or brown staining and slimy deposits that won’t scrub off, repeated need for cleaning at much shorter intervals than usual, and pieces of filter material in the pool. Also note age: even if a cartridge looks okay, once it’s past the manufacturer’s recommended life and you’re seeing any of these symptoms, replacement is the safer choice. Keep a spare cartridge on hand so you can swap it quickly and avoid running the pump with a compromised filter.
There’s no single timetable that fits every pool, but a good rule of thumb is to expect cartridge replacement somewhere around the 3–5 year mark for typical residential use, sooner for heavy use or harsh environments. Watch for visible damage, persistent pressure and clarity problems, and a loss of cleaning effectiveness—those are the practical signs that tell you replacement is due. Regular maintenance and attention to pool chemistry will extend the life of your cartridge, but planning and timely replacement will keep your pool water clear and your equipment running efficiently.