Tetra Pond Algofin. It can also be used as an effective deterrent for green water. Add 50ml of AlgoFin for every 1000 litres (220 gallons) of pond water. HSE approved algaecide for blanketweed. Blanketweed and algae can easily and quickly build up in your pond water and can pose a threat to the life of the fish and plants living in the water.
eBay