Backwashing a pool filter—washing the material that filters your pool water—helps keep it running properly. It's a great way to ensure a cleaner, safer pool season. But each type of filter requires a slightly different protocol to backwash. Here's how to manage the three most popular types of filters.
Sand filters work best when they're on the dirty side—the additional dirt can actually help block small particles of dirt and impurities from circulating back into the pool. You should backwash the filter only when the filter pressure moves up 10 to 15 lbs. from where it is when it's clean. (Usually, this is needed once every few weeks.)
Diatomaceous Earth Filters
These use skeletons of diatoms, small sea creatures, to filter your water. Again, backwash the filter when the pressure goes about 10 lbs. from where it is when it's clean. DE filters require switching back and forth from the "filter" to the "backwash" settings several times during the backwashing process, a few minutes at each setting. Many DE filters also require adding more diatomaceous earth after backwashing.
These filters, similar to the air cleaning filter in your car, do not require backwashing at all. Instead, shut off the filter pump, remove the cartridge and hose it down until it's clean. You should only have to do this once or twice a season, and replace the filter every few years.