Fluval Polishing Pad. Fluval Water Polishing Pads are uniquely designed to fit Fluval Canister Filters. These extra thick micro-fine polyester pads effectively trap micro particles and debris as water passes through. For freshwater and marine environments. Key Features : Mechanical filter media Produces crystal clear aquarium water Extra thick, micro-fine polyester pads effectively trap micro-particles and debris Ideally used when cloudy water occurs or after tank maintenance.