Key Features Tackles Duckweed at its root Effective and easy to use Safe for fish Helps to starve Duckweed of nutrients to prevent further growth 1 Litre treats 22750 Litres (5000 Gallons) If Duckweed forms on a pond surface, it can become unsightly and makes it more difficult to view the fish and wildlife in the pond. Banish Duckweed Clear is an advanced multi-action product to successfully remove the problem from pond water. Banish Duckweed Clear is the only product on the market to tackle duckweed through its roots and leaves, starving it of nutrients it needs to survive and thus it is the only successful way to remove this problematic aquatic weed. The treatment is simple to use. Just add 10ml of treatment per 225 litres (50 gallons) once to the pond, repeat after a week if needed. Do not use on established and ornamental pond plants.