Providing you with quality you can trust, the Pro Series top mount high-rate sand filters incorporate the latest pool filter technology to ensure your pool is operating at its very best. Molded of durable, corrosion-proof reinforced thermoplastic, they feature attractive, unitized tank construction for years of trouble-free operation with only minimal care. Pro Series sets a new standard for performance, value and dependability. In this method, impurities are extracted from the water using sand to collect and attract the debris as small as 20 to 40 microns. Sand filters must be backwashed (running it in reverse) to unload the water waste.