Tetra Pond Algae Control - Green Water & String AlgaeTetra Pond Algae Control effectively combats: Algae blooms(green water). String and hair algae(Spirogyra). Blanket weed(Oedogonium). For use only in fountains and ornamental ponds with synthetic liners. Controls string and hair algae Controls blanket weed Safe for ponds with fish and plants Can be used with plants and ornamental fish when used as directed. Do not use in ponds with invertebrates or crustaceans (e. g. crabs, shrimps or crayfish).