Fountec Fountain Algaecide Clarifier, 64 Ounce Fast acting and no chlorine needed Kills and inhibits all types of algae growth in all types of water fountains and ponds Treats over 2400 U.S. Gallons with recommended dosage: one drop per gallon of water per week Keeps Water Crystal Clear and Algae-Free Kills & Prevents Algae Growths