The Perflex Extended-Cycle DE filter series cleans pools fast — removing the smallest particles the first time through. That’s because Perflex incorporates a patented Flex-Tube design that works in combination with DE (diatomaceous earth) filter powder to produce the clearest, most sparkling water possible.The exclusive Perflex Extended-Cycle gives you long filter cycles between cleaning — up to eight weeks depending on pool size and use. Because the same filter powder is used over and over again, Perflex is a real work saver. And, it only takes minutes to extend the cycle.Perflex filters stretch your dollars too! Since Perflex cleans without backwashing, you save hundreds of gallons of treated pool water. Plus, Perflex saves on electricity because its efficient design offers less resistance to flow and produces more filtered water with less pump horsepower.