API Pond Algaefix for Ponds API has been an industry leader in fish care, nutrition, treatments, testing and pond products for over 50 years, giving them a keen insight into your aquarium and its needs - making them the clear choice for fish enthusiasts around the world. API Pond Algaefix effectively controls green water algae blooms, string or hair algae (Cladophora), and blanketweed (Oedogonium) in ponds containing live plants and fish. This algae control is fast-acting, controls algae growth, controls the formation of new algae, and helps resolve algae problems. Registered with the EPA, this product controls many types of algae in water gardens, ponds, and ornamental fountains containing live plants and fish. Algae control for Saltwater Aquariums Controls green water algae blooms, string / hair algae (Cladophora), and blanketweed (Oedogonium) Suitable for ponds, ornamental fountains, and garden ponds Caution: Before using Pond AlgaeFix, make certain that the pond has vigorous aeration, i.e. a fountain or aeration device to avoid fish loss due to low oxygen levels. When algae is controlled and removed by the filter or settles to the bottom of the pond, the oxygen level may drop to harmful levels if aeration is not provided. In warm weather, pond water carries much less oxygen. Therefore when using Pond Algaefix during warm weather and high water temperatures, vigorous aeration is required for the duration of the treatment. Do not shut off pond pumps and aeration devices at night.