A cartridge filter removes dirt, leaves and other fine debris as water circulates through your pool system. As the cartridge collects debris, water flow decreases and pressure inside the filter rises.
Regular cleaning helps maintain circulation, reduces strain on the pump and gives you an opportunity to inspect the cartridge before a small problem affects the rest of the system.
Safety first: Pool filters operate under pressure. Always follow the instructions for your specific filter. Turn off the pump and automatic controls, relieve all pressure and confirm that the gauge reads zero before opening the filter. If you are uncertain about any step, contact a qualified pool professional.
How Often Should You Clean a Pool Cartridge Filter?
There is no single cleaning schedule that applies to every pool. Cleaning frequency depends on the size of the filter, swimmer use, surrounding trees, weather and water conditions.
The pressure gauge is usually a better guide than the calendar. Record the filter’s pressure when the cartridge is clean and the pump is running at its normal speed. Many manufacturers recommend cleaning when the pressure reaches approximately 8 to 10 PSI above that starting pressure or when water flow drops noticeably.
Pentair recommends cleaning its Clean & Clear Plus cartridge filters when pressure is approximately 10 PSI above the original starting pressure. Always confirm the instructions for your own model in its manual or on the manufacturer’s filter safety and support page.
What You Will Need
Before starting, gather:
- A garden hose with a standard spray nozzle
- Safety glasses and gloves
- The filter manufacturer’s instructions
- A replacement tank O-ring if the existing one is damaged
- Manufacturer-approved O-ring lubricant, if required
- A cartridge-cleaning product for deeper cleaning, if recommended
Do not use a pressure washer. High-pressure water can damage the filter material and shorten the cartridge’s life.
How to Clean a Pool Cartridge Filter
Shut Down the Pool Equipment
Turn off the pump and disable any timer or automation that could restart it while you are working.
Close the required valves according to the instructions for your pool system. Never loosen the filter clamp or lid while the system is operating or under pressure.
Relieve the Pressure
Open the manual air-relief valve and wait until air and water stop escaping. Check that the pressure gauge has returned to zero before proceeding.
If the gauge does not return to zero, do not open the filter. The gauge may be damaged and should be inspected or replaced.
Open the Filter Housing
Follow the manufacturer’s directions to remove the clamp, locking ring or filter lid. Different models use different closure systems, so do not force any component.
Carefully remove the cartridge or cartridge assembly and place it on a clean surface.
Rinse the Cartridge
Use a garden hose to rinse between the pleats, working from the top toward the bottom. Take your time and move around the entire cartridge so debris is removed from both the outside and between the folds.
Avoid using a stiff brush, pressure washer or sharp tool. These can damage the filter material.
Deep-Clean When Necessary
A hose rinse may not remove sunscreen, body oils, scale or other stubborn buildup. If the cartridge remains dirty, use a cleaning product approved by the filter manufacturer.
Follow the product directions for dilution, soaking time and disposal. Never mix pool chemicals or cleaning products.
Inspect the Cartridge
Before reinstalling it, check for:
- Torn or frayed filter material
- Crushed or flattened pleats
- Cracked end caps
- Loose bands
- Warping or structural damage
- Debris that cannot be removed
A damaged cartridge should be replaced rather than returned to service.
Inspect the Filter Tank and O-Ring
With the filter open, inspect the tank, lid, clamp or locking ring and sealing O-ring. The O-ring should be clean, flexible and free of cracks or deformation.
Use only a lubricant approved by the manufacturer. Petroleum-based products can damage some O-rings and should not be substituted.
If the clamp, tank or lid appears damaged, do not restart the system until it has been inspected by a qualified professional.
Reassemble and Restart the Filter
Reinstall the cartridge in the correct position and reassemble the filter exactly as described in the manual. Make sure the sealing surfaces are clean and the closure mechanism is properly secured.
Stand clear of the filter while restarting the pump. Keep the air-relief valve open until a steady stream of water appears, then close it according to the manufacturer’s instructions.
Check the tank, lid, connections and drain for leaks. Record the clean starting pressure for future reference.
Shut the system down immediately if you notice leaking, unusual noise, an incorrect pressure reading or a failure to establish normal water flow.
When Should a Filter Cartridge Be Replaced?
A cartridge does not need to be replaced simply because it looks stained. Replacement may be necessary when:
- The filter material is torn or frayed
- Pleats remain flattened after cleaning
- End caps are cracked or separated
- Bands are broken
- The cartridge no longer comes clean
- Pressure remains high after proper cleaning
- Water clarity or flow does not improve after other causes are ruled out
Cartridge life varies considerably. Pool use, water chemistry, cleaning methods and the size of the filter all affect how long it lasts.
Help Your Cartridge Filter Last Longer
Good pool habits reduce the amount of debris reaching the filter:
- Empty skimmer and pump baskets regularly
- Maintain the correct pool-water level
- Skim leaves before they sink
- Keep water chemistry properly balanced
- Clean up heavy debris after storms
- Avoid running damaged pool-cleaning equipment
- Use a pool cover when appropriate
If pressure suddenly drops rather than rises, check the water level, skimmer basket and pump basket. A low reading can indicate restricted water entering the pump or another circulation problem.
Pool Filter Replacement and Equipment Upgrades
Cleaning cannot repair a damaged cartridge or an aging filter system. If your pool has ongoing circulation problems, leaks or equipment that is difficult to maintain, it may be time for an inspection or replacement.
Earthworks Landscaping & Pools supplies and installs pool filters and other equipment for homeowners in Burlington, Oakville and surrounding communities. Explore our pool equipment services or contact us to discuss a replacement or upgrade.
