Rena Filtration Foam 20 (20 ppi) is a coarse pre-filter stage designed to trap debris and solid waste before water reaches your chemical and biological filtration. Its open-cell design ensures unrestricted water flow through your FilStar canister filter. Simply place in the bottom basket, rinse every 2-4 weeks under running water, and replace after several months of use. Reusable and washable for
