Ultra PondWeed Defense works on active and growing pond weeds including submerged, floating and emergent weeds. Pond Logic Ultra PondWeed Defense may be used for short term control of duckweed in slow moving water. Use all season long on actively growing weeds for best results. Mix 3 gallons of water per quart of Ultra PondWeed Defense to treat 5,000 sq ft. Can be used on lily pads, water hyacinth, hydrilla, naiad, various pondweeds, etc.