Pack of two algae removing replacement cartridges for the aquarium systems cobra internal filter range as well as other internal external filtersr 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 aquariumsr 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