Replace a Pool Filter Cartridge in 4 Steps

Both in-ground and above-ground pools use pool filter cartridge units to filter the water. These are the simplest of all filter systems to maintain. If you choose this type for your pool, purchase the most up-to-date system you can buy, as the filters now have a service life of between 2 and 3 years. With careful and regular cleaning you will get full life from them, and dazzling clean pool water for you and your family and friends to enjoy.

How to Know When Cartridges Must Be Replaced

Two indicators will tell you that cartridges are full and must be replaced. First, the swimming pool water is no longer looking crystal-clear, and even large visible particles are not being strained out. Second, the filter pressure gauge is well above normal and does not drop when the cartridge is cleaned and rinsed. Follow the step-by-step procedure below to replace a clogged cartridge.

Step 1: Check the Cartridge Unit Pressure Gauge

  • The normal pressure on this gauge should read 12 pounds.
  • If it reads 22 or more pounds (10 pounds or more above normal), remove and check the pool filter cartridge as usual for cleaning.

Step 2: Clean and Rinse the Cartridge as Usual

  • Clean and rinse the cartridge, and reinstall it.
  • If the pressure does not drop back to the normal reading right away, take the cartridge out again.
  • Soak it in a large sink or tub with a weak solution of trisodium phosphate for 5 minutes, as in the directions. This will help remove accumulated grease and oil from sunscreens and tanning products that can clog the filter vanes.
  • Rinse thoroughly and put the cartridge back in the filter unit.
  • If, even after this treatment, the filter pressure does not decline to its normal level, the cartridge may no longer be usable.

Step 3: Troubleshoot the filter gasket

  • Before replacing the cartridge, check that the filter unit lid gasket, found inside the lid, is seated in the correct location, and is making a tight seal.
  • If the filter unit lid gasket is out of place, the suction of the filter will not be tight and the filter may not operate properly. This can also cause the pressure gauge to give an inaccurate reading.
  • Refasten the lid and start the filter once more to confirm the seal is tight.
  • If pressure still does not drop to normal, replace the pool filter cartridge.

Step 4: Replace the Cartridge

  • Obtain a new cartridge from your dealer or from a reputable pool equipment retailer.
  • Rinse the cartridge with water as directed.
  • Insert the new cartridge into the filter unit.
  • Activate the filter unit, and check the filter pressure. If it has returned to normal pressure, the filter will operate properly again.
  • Upon replacing the filter, continue to clean it when prompted to do so by a rise in the filter pressure. When you close the pool for winter, dunk the cartridge in the trisodium phosphate solution and rinse thoroughly, to ensure it is clean and ready to work for next summer.