API WATER SOFTENER PILLOW Aquarium Canister Filter Filtration Pouch is a chemical filtration media that reduces general hardness found in tap water for aquarium use. WATER SOFTENER PILLOW works to lower calcium and magnesium levels, and also removes heavy metals and reduces white, crusty mineral deposits on aquarium surfaces. WATER SOFTENER PILLOW can be reused after it is recharged in a salt solution. Use when starting or maintaining an aquarium when testing indicates water hardness above the desired level. Use according to directions on product packaging. 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 are designed to work in conjunction with each other to provide best results to control algae, promote healthy bacterial growth and help control and cure fish diseases and conditions such as ich and fin rot. They 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.