23mg of milbemycin oxime treats 380-400 gallons. Milbemycin oxime is the active ingredient in the pill. The large breed pill weighs about 1 gram and has 23mg of milbemycin in it. The dosage used in the treatment is based on the entire interceptor pill, not the active ingredient. Meaning you use 25mg of interceptor per 10 gallons of water.