Reagent grade ammonium chloride to add ammonia to the aquarium when first cycling an aquarium without fish. Generally during a fishless cycle one needs to add ammonium chloride to their tank 3 or 4 times.
Concentration is 50 mg/L of total ammonia-nitrogen (TAN). Dose 1 drop per gallon of aquarium water. Use with One and Only Nitrifying Bacteria.