Pack of two Algae Removing replacement cartridges for the Aquarium Systems Cobra Internal Filter Range and other internal/external filters. Newaqua Algo Out is a special anionic resin unique of its kind. Its chemical characteristics and the fact that it is particularly macroporous enable it to eliminate nitrates selectively and stop algae growth. The particular dimensions and spherical structure of Newaqua Algo Out 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 Out 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 Out is recommended for Freshwater and Marine alike, where it selectively eliminates nitrates, even in the presence of high sulphate concentrations.