API Stress Zyme Improves the development of the biological filter and helps clean a dirty aquarium. It contains over 300 million live bacteria per teaspoon. Breaks down organic compounds that cause dangerous conditions such as ammonia and nitrite poisoning and low oxygen levels. Continuous use assures an active biological filter, cleaner aquarium, healthier fish and good water quality. No refrigeration necessary. Use when setting up and maintaining an aquarium. For use in fresh and saltwater. Purpose and Benefits: Stress Zyme is a biological filter additive containing live bacteria that improves the development of the biological filter and helps clean a dirty aquarium. The build-up of organic pollution in the aquarium inhibits the growth of nitrifying bacteria. The bacteria in Stress-Zyme keep conditions in the aquarium right for the development of the biological filter by consuming harmful organic pollutants. This speeds the development of the biological filter in newly set up aquariums. A build-up of organic compounds also promotes the growth of disease-causing organisms in the aquarium. Stress Zyme keeps the biological filter working properly by keeping the aquarium gravel and filter clean. Water quality and living conditions are improved when Stress Zyme is used on a regular basis.Each teaspoonful of Stress Zyme contains 300 million bacteria. These bacteria are in a dormant state and become active when added to the aquarium. Stress Zyme has a five year shelf life and does not require refrigeration. Stress Zyme is effective in freshwater and marine aquariums. Directions for Use: New Aquariums: Shake well before using.On the 1st, 7th, and 14th days add 2 teaspoonfuls (10 ml) for every 10 US gallons (40 L) of aquarium water. Thereafter, each week add 1 teaspoonful (5 ml) for every 10 gallons (40 L) of aquarium water. Existing Aquariums: To maintain good water quality and healthy biological filtration, add 1 teaspoonful (5 ml) for every 10 U.S. gallons (40L) of aquarium water weekly. Compatibility: Stress Zyme can be used with freshwater tropical fish, marine fish, invertebrates and coldwater species including koi and goldfish. Stress Zyme will not harm aquatic plants. Keep from freezing. Do not store above 120F (49C). Stress Zyme is completely harmless to humans and pets.