Healthy Ponds 52350 Refills for All Purpose Pond & Water Cleaner 1,000; 3 30-Day Refills Treat up to 1,000 Gallons for 90 Days Keeps small ponds and water features (aquariums, fountains, etc.) From 100-1,000 gallons clean, clear and free of green organic growth Unique patented time-release system delivers a proprietary blend of naturally occurring bacteria and enzymes into the water for 30 days Veterinarian approved and safe for fish, plants, birds, animals and humans Results may vary; over time bacteria and enzymes will work to reduce organic debris, improving water quality and clarity while eliminating odor 3 30-day refills; treats up to 1,000 gallons for 90 days