2 oz (59 ml) bottle of reagent grade ammonium chloride for use when fishless cycling. Concentration is 50 mg/L of total ammonia-nitrogen (TAN). Dose 1 drop per gallon of aquarium water. 1 drop equals 0.05 ml so this bottle will treat 1,180 gallons. Generally during a fishless cycle one needs to add ammonium chloride to their tank 3 or 4 times so this bottle is enough ammonia to cycle aquariums up to 250 gallons.