Renew your filter with this Filter Renu cleaner! Use this granulated compound cleaning agent for sand, cartridge, and DE (diatomaceous earth) filters. Add through the skimmer and allow it to remain in the filter for 30-to-40 minutes. Then backwash to purge out dirt, oils, minerals and organic matter from filter systems. Add once a month to remove scale and rust. With this its easy to improve water clarify and maintain filter efficiency.