Establishes biological filtration quickly! Freshwater Zym Bac contains species of nitrifying beneficial bacteria needed to start or accelerate the nitrogen cycle of biological filtration for aquaponics, aquariums and ponds. 4 oz will treat up to 10 gallons of water 8 oz will treat up to 20 gallons of water 16 oz will treat up to 40 gallons of water 1 gal will treat up to 320 gallons of water