When left uncorrected, high nitrate in aquarium water can lead to water problems invisible to the eye, poor fish health and a build-up of organic pollutants. It is recommended to test water weekly. API NITRA-ZORB is a filtration media in a pouch format that works to remove harmful toxins, such as ammonia, nitrate, and nitrite, from freshwater aquariums. API NITRA-ZORB reduces the risk of fish loss when starting or maintaining an aquarium. API NITRA-ZORB can be reused after being recharged in a salt solution. Fits most canister filters on the market. 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 are designed to work in conjunction with each other to provide best results promote healthy growth and help fish 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.