Aquarium Pharmaceuticals FilStar Micro-Filtration Pad Removes extremely fine waste, sediment, and particles from waterL Helps clear cloudy waterL "Polishes" water to help make it crystal clear UL&gt; Directions for use in all RENA FilStar Filters:B Place pad in last filtration compartment, above all other filter media.L Replace pad once a month or sooner if it becomes clogged or if filter flow diminishes.