Keeping your spa's filter clean is a major part of keeping your water clean. Without a clean filter, none of your other water care efforts will amount to much, since all your spa's water flows through the filter...plus, many costly equipment failures can be avoided just by keeping your filter clean. Here are some filter cleaning tips from Unicel, one of the biggest manufacturers of spa and pool filters.
*Please note* These cleaning instructions are only for spas using chlorine or bromine as their sanitizer. Spa owners using biguanide sanitizers (such as Baquacil, Baquaspa, or Softswim) should consult their manufacturer's instructions to clean their filters.

The filter cartridge should be cleaned when the filter canister pressure reaches a maximum of ten pounds per square inch (10 PSI) above the initial system or new cartridge starting pressure. It would be helpful to mark the new cartridge or system starting pressure on the pressure gauge with a grease pen or nail polish.

If there is no pressure gauge on the filter, establish a maintenance schedule based on bather load. For example, if the bather load is light, rinse the cartridge monthly and soak it in cleaning solution every third or fourth month. If bather load is heavy, rinse the cartridge weekly and soak it monthly.

To clean the filter cartridge:
  • Remove the cartridge from the filter housing (see manufacturer's instructions).
  • Rinse the cartridge with a garden hose to remove all loose debris. Take care to remove all foreign matter from between the pleats. If the cartridge is heavily soiled, a high pressure nozzle on the garden hose can be used.
  • To remove oils, soak the cartridge for eight hours or overnight in a solution of either one cup tri-sodium phosphate (T.S.P.) or one cup automatic dishwashing detergent to five gallons of water.
  • Rinse the cartridge thoroughly before putting it back in the filter housing.