Aquarium Product Biozyme has living nitrifying bacteria and enzymes. In their natural habitat, fish rely on microorganisms to clean their waste matter, which later become their own source of protein in the form of protozoa and other smaller species of aquatic life. In a newly set-up aquarium, these microorganisms do not exist. Biozyme helps produce this type of habitat while also reducing New Tank Syndrome.Saltwater Biozyme can be used with the lowest form of invertebrates safely. It can even be used in "reef type" aquariums, too! For first dose, use 1/4 teaspoon for each 25 gallons of water directly in the aquarium. Every week, add 1/8 teaspoon per 25 gallons to avoid pollution and for nitrate reduction. 8 grams treats 500 gallons.Freshwater Biozyme - For first dose, use 1/4 teaspoon for each 25 gallons of water directly in the aquarium. Every week, add 1/8 teaspoon per 25 gallons to avoid pollution and for nitrate reduction. 8 grams treats 500 gallons.