ST International Gold Nitrifying Bacteria Highest concentrated Nitrifying and Beneficial Solution on the Market Contains nitrifying and beneficial bacteria strains with an extremely powerful decomposing capacity Toxic ammonia and nitrite are transferred to a safe state, like nitrate and organic compounds in the aquarium are broken down to purify water Can rapidly jump-start the proper biological filter system for a new aquarium and maintain a safe and stable filtering environment Available in 100ml (3.4 flu oz.), 250ml (8.4 flu oz.), 500ml (16.9 flu oz.) and 4000ml (1 US Gal.)