API Quick Start nitrifying bacteria allows for the instant addition of fish, as it immediately starts the natural aquarium cycle with beneficial bacteria, which converts toxic ammonia into nitrite, then into harmless nitrate to help prevent fish loss in your tank. Best for use when starting a new aquarium, after water changes and filter changes, and when adding new fish to an existing aquarium. API Quick Start nitrifying bacteria may be used in both fresh and saltwater aquariums. pH Balance 6.9 - 7.7 pH Use Instructions Use when starting a new aquarium, adding new fish, changing water, changing filter media, after medicating, or whenever ammonia or nitrite are detected. Use the API dosing cap on bottle. Shake well. Add 10 ml per 10 U.S. Gallons (38 L) of aquarium water. For saltwater aquariums, double the dose. Caution Keep out of reach of children. Keep from freezing. Store in a cool place.