Depending on the size of the filter, you should clean it from once a week, to once a month. It should last a couple of years, at least....
1. Remove the cartridge from the filter housing following the manufacture’s instructions.
2. Use a garden hose with a straight flow nozzle to wash down the filter element. Work from the top down, holding the nozzle at a 45 degree angle, and wash all the pleats with emphasis between pleats.
3. Rinse until all dirt and debris is gone.
4. For all spa cartridges and elements used in swimming pools where perspiration, suntan lotions, and other oils are present, soak the element for at least one hour (over night is more effective) in (1) a commercial filter cleaner; or (2) one cup trisodium phosphate (TSP) to five gallons water; or (3) once cup dishwasher detergent to five gallons of water.
5. Rinse the cartridge again to remove oils and cleaning solution.
6. If the filter has a coating of algae, calcium carbonate (residue from calcium hypochlorite), iron, or other minerals, soak the cartridge in a solution of one part muriatic acid to twenty parts water until all bubbling stops. WARNING: Failure to remove all oils and cleaning solution before acid soaking will result in a permanent restriction of water flow and cause premature cartridge failure.
7. Rinse the cartridge clean an reassemble housing.