Check the listing for details. Ammonium Chloride for Fishless Cycling - Dr Tim's (2 oz). Condition: New. Listed at 5.96 USD. This bottle of reagent grade ammonium chloride is for use when fishless cycling. Concentration is 40 mg/ml of total ammonia-nitrogen (TAN). Dose 4 drops per gallon of aquarium water.* Use with One and Only Nitrifying Bacteria. Generally during a fishless cycle you need to add ammonium chloride to your tank 3 times so: a 2 ounce (60 ml) bottle will cycle 100 gallons (359 liters) a 4 ounce (120 ml) bottle will cycle 200 gallons (757 liters) a 8 ounce (480 ml) bottle will cycle 400 gallons (1,514 liters) Some conversions: 1 drop equals 0.05 ml 1 ml equals 20 drops 1 teaspoon equals about 5 ml which is 100 drops 1 tablespoon equals almost 15 ml which is 300 drops *NOTE: As of November 1, 2016 we changed the concentration of the ammonium chloride solution so it now takes 4 drops per gallon. The previous version called for 1 drop per gallon. Please see the label on your bottle to determine how much to use. If the bottle says use 1 drop use 1 drop if the bottle says use 4 drops use 4 drops. Listing and template services provided by inkFrog