Pack of two Algae Removing replacement cartridges for the Aquarium Systems Cobra Internal Filter Range as well as other internal / external filters Newaqua Algo Prevent is a special synthetic resin with a very large microporous surface area. It has been purpose-designed to absorb phosphates and silicates in freshwater and saltwater aquariums. The high quality of this product is explained by the low percentage of water that it contains (less than 1%). This guarantees maximum efficiency in terms of absorption and offers a cheap solution for tropical fish hobbyists. The particular dimensions and spherical structure of Newaqua Algo Prevent prevent not only compacting inside the filter but also guarantee a perfect contact surface with the water flow, optimising efficiency and life span (up to 6 months).Continuous use of Newaqua Algo Prevent provides ongoing pollution control and effectively prevents the development of undesirable algae inside the tank, while helping to improve the living conditions of the aquarium\'s residents.Newaqua Algo Prevent is recommended for Freshwater and Marine alike.