API Stress Zyme Plus Biological Filtration Booster: 1 oz - (Treats 60 Gallons) #56A Stress Zyme by Aquarium Pharmaceuticals helps improve the development of the biological filter, as well as cleaning a dirty aquarium. API Stress Zyme breaks down Organic Compounds that can cause dangerous conditions such as Ammonia and Nitrite poisoning and low oxygen levels. Healthier Fish and Overall Water Quality Improve the Development of the Biological Filter Contains millions live bacteria to destroy gravel bed sludge Can be used in Freshwater & Saltwater Aquariums A continuing use of Stress Zyme will assure an active biological filter, cleaner aquarium, healthier fish, and an overall good water quality. You do not have to keep this product refrigerated. StressZyme can be used in Fresh or Saltwater aquariums and when setting up or maintaining aquarium.