Nitrofurazone Powder 100%, 100 grams. USE: A good disinfectant for clearing water prior to newly arrived fish. Effective against marine ulcer disease and protozoans. Also useful in treating furunculosis found in Koi. DOSAGE: 1/4 teaspoon per 20 gallons. 250 grams (treats approx. 4000 gallons) Treat every 24 hours with a 50% water change before each treatment. Treat for 10 days.