How to Clean a Pool Filter: The Ultimate Guide for Cartridge Systems
If your pool uses a pleated cartridge filtration system, you benefit from excellent water clarity and zero wasted water since there is no backwashing involved. However, knowing exactly how to clean a pool filter of this type is crucial. Because cartridge filters rely on delicate, woven polyester fabric to trap dirt down to 10 microns, they must be handled with care. Aggressive cleaning methods can instantly destroy the micro-pores, turning a $100 filter into useless plastic.
When is it Time to Clean the Cartridges?
Do not guess. Look at the pressure gauge on top of the filter tank. When the pressure reads 8 to 10 PSI above the starting pressure (the baseline pressure established when the filters were brand new), it is time to take them out and wash them. For most residential pools, this occurs every 3 to 6 weeks.
Step 1: Depressurize and Open the Tank
Safety first. Turn off the pool pump at the breaker. Next, open the air relief valve on top of the filter tank to release the trapped hydrostatic pressure. Once you hear the hissing stop, loosen the belly band clamp or unscrew the locking knob to remove the lid. Carefully lift the cartridges out of the manifold.
Step 2: The Proper Rinsing Technique
Take the cartridges to an area with good drainage. Using a standard garden hose equipped with a spray nozzle, start at the top of the cartridge and spray downward at a 45-degree angle.
- Work your way down, flushing the dirt out from between the pleats.
- Rotate the cartridge slowly to ensure every single pleat is rinsed.
- NEVER use a pressure washer. The intense PSI will blast microscopic holes into the fabric, allowing dirt to pass directly back into your pool.
- NEVER use a stiff bristle brush. It will fray the polyester fibers and cause the filter to fail prematurely.
Step 3: The Chemical Degreasing Soak
Rinsing with a hose only removes loose dirt, leaves, and bugs. It does not remove the sticky invisible layer of sunscreen, sweat, cosmetics, and body oils that clog the microscopic pores. At least twice a year, you must chemically clean the cartridges.
- Fill a large plastic trash can with water.
- Add a specialized pool filter degreaser or a cup of Trisodium Phosphate (TSP).
- Submerge the cartridges completely and let them soak for 12 to 24 hours.
- Remove them and rinse them thoroughly with the hose before reinstalling them in the tank.
Step 4: Reassembly and Air Bleeding
Place the clean cartridges back into the manifold. Before putting the lid back on, wipe the large rubber O-ring clean and apply a fresh coat of silicone or Teflon pool lubricant. Secure the lid clamp tightly. Turn the pump back on while leaving the air relief valve OPEN. Wait until a steady stream of water shoots out of the valve, then close it. Your filter is now perfectly clean and pressurized.
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