API FILSTAR FILTRATION FOAM is the ideal thickness to filter small waste particles in aquarium water. Serves as part of the mechanical filtration for API FILSTAR XP. Dual-density pad is effective for approximately one month of use. Use as directed on product label. With API Aquarium products, it's easy to keep a beautiful saltwater, freshwater or reef aquarium. For over 50 years, API has been creating innovative, research-driven solutions that make it easier to care for your fish and aquarium. API Aquarium Treatment Supplies work to provide a safe, hospitable environment for fish such as tropical community fish, cichlids, goldfish and more. With API, you can spend more time admiring your fish, and less time scrubbing your tank. Make sure to use all products as directed in order to ensure the best results.