How often should I backwash my filter?
In sand and DE filters, water flow is reversed in the filter to clean out debris (backwashed). At start up or after the filter has been cleaned, check the filter pressure. As the filter gets dirty the pressure will rise. Once the pressure has risen 5 to 7 lbs. it is time to backwash. DE filters need to be broken down and cleaned every 6 months. Sand filters need to have sand changed about every 5 years, depending on the alkalinity & calcium content of the water in the pool. Cartridge or modular media filters are cleaned by removing the cartridge & hosing them out with high pressure nozzle. Again the 5 to 7 lbs. rise on the filter pressure will tell you when to clean the filter. On smaller cartridge filters 100 to 150 sq. ft., expect to clean about every 10 days, on larger cartridge filters 300 to 450 sq. ft., expect cleaning every 6 months.