The PoolRX 101066 Black Unit Algaecide for 20000 to 30000 Gallons is part of the PoolRX products which is developed to be a unique chelated mineral algaecide and chemical reducer that is effective for up to 6 months. It is the recommended algaecide solution for all chlorine pools, salt pools and spas which is suitable for Residential and Commercial use. It can be placed in a pump basket or skimmer where its minerals can function immediately and eliminates all types of algae so you can have an improvement in your salt or regular pool swimming experience. This product provides a 50 percent reduction in your chlorine or salt chlorine demand and a 100 percent elimination of the need for harsh chemicals like phosphate removers, clarifiers, sodium bromide, and other chemicals. It can also descale the salt cell in your chlorinators which is equal to prolonging the life of the cell. PoolRX is very ideal to use with Chlorine, Salt, UV or Ozone systems.