Sand filter

A sand filter pushes water through a bed of sand. Dirt stays in the sand until you backwash. It is simple and tough, and it needs little work.

Backwash when the pressure gauge rises, then rinse. The sand wears smooth over the years, and it stops trapping fine particles. See filter sand. If the pool stays cloudy after a good backwash, the sand may need replacement. A multiport valve controls the process. Ask a pro to check for leaks.