How Long Do Pool Cartridge Filters Last? Replacement Guide

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Quick Answer

Your pool cartridge filters will last 1-4 weeks between cleanings and need complete replacement every 3-6 months. High-use pools, heavy bather loads, and environmental factors like algae blooms or storms can shorten this timeframe significantly.

Cleaning vs. Replacement Schedule

Between Cleanings: 1-4 Weeks

The time between cleanings depends on several factors:

• Pool usage: Heavy bather load reduces time to 1-2 weeks
• Environmental conditions: Pollen, dust, and debris shorten intervals
• Water chemistry: Poor balance leads to faster clogging
• Filter size: Larger surface area lasts longer between cleanings

Complete Replacement: 3-6 Months

Even with regular cleaning, cartridge filter media eventually breaks down. Replace filters when you notice:

• Pleats starting to fray or separate
• Filter media becoming discolored or stained
• Cleaning becomes less effective
• Pressure differential increases quickly after cleaning

Signs Your Filter Needs Attention

Time to Clean (Weekly Check)

Monitor your pressure gauge weekly. When pressure rises 8-10 PSI above the clean starting pressure, it's time to clean your cartridges. For example, if your clean pressure is 12 PSI, clean when it reaches 20-22 PSI.

Time to Replace (Monthly Assessment)

Inspect cartridges monthly for these replacement indicators:

• Frayed pleats: Media separating from the plastic frame
• Permanent staining: Brown, green, or yellow discoloration that won't clean off
• Shortened cleaning cycles: Pressure rises faster than usual after cleaning
• Visible wear: Thin spots or holes in the filter media
• Poor water clarity: Cloudy water despite proper chemistry

Factors That Affect Filter Life

Pool Usage Patterns

Bather load dramatically impacts filter life. Each swimmer introduces oils, lotions, hair products, and organic contaminants. A busy family pool or one used for entertaining will require cleaning every 1-2 weeks, while a lightly used pool might go 3-4 weeks.

Environmental Conditions

Your location affects filter longevity:

• Windy areas: More debris means more frequent cleaning
• Trees nearby: Leaves, pollen, and organic matter reduce intervals
• Dusty climates: Fine particles clog filters faster
• Rainy seasons: Increased organic growth and debris

Water Chemistry Balance

Proper water balance extends filter life significantly. Maintain these TFP-recommended levels:

• pH: 7.4-7.6 for optimal filtration
• Free Chlorine: Follow FC/CYA chart (typically 2-4 ppm)
• Total Alkalinity: 60-80 ppm for SWG, 80-120 for regular chlorine
• Calcium Hardness: 250-350 ppm for plaster pools

Poor chemistry leads to algae growth, scale formation, and increased organic loading that clogs filters rapidly.

Maximizing Filter Lifespan

Rotation System

Use a two-set rotation system. While one set filters your pool, the other set air-dries completely. This rotation extends total filter life by 30-50% and ensures you always have clean filters ready.

Proper Cleaning Technique

Clean cartridges with a garden hose spray nozzle, working from top to bottom at a 45-degree angle. Avoid pressure washers, which damage the filter media. For deep cleaning, soak overnight in a cartridge cleaner solution or a 10:1 water-to-muriatic acid solution (wear safety gear).

Chemical Balance Maintenance

Test water 2-3 times weekly using a Taylor K-2006C test kit. Maintain proper sanitizer levels to prevent algae growth that rapidly clogs filters. If water turns green, immediately begin a SLAM process using liquid chlorine to restore clarity and reduce filter strain.

When to Replace Prematurely

Sometimes filters need early replacement:

• After algae blooms: Green water events can permanently stain and clog filters
• Following storms: Heavy debris loads may damage filter media
• Chemical accidents: Over-chlorination or pH swings can degrade filter material
• Winter damage: Freezing can crack or damage cartridge frames

Cost-Effective Filter Management

Quality cartridge filters cost $15-40 each, making replacement a significant expense. Extend value by:

• Buying filters in bulk during sales
• Maintaining proper water chemistry to prevent premature clogging
• Using a skimmer basket and leaf trap to reduce debris load
• Showering before swimming to reduce oils and lotions

Safety Note: When using muriatic acid for deep cleaning, always wear gloves, eye protection, and work in a well-ventilated area. Add acid to water, never water to acid.