The Hel-X 13 biomedium breaks down nutrients and pollutants extremely effectively using the fluidised bed method. The latest development of this filter medium impresses with a sensational surface area of 955 m² per m³ and an extremely large, protected colonisation surface for microorganisms of 806 m² per m³. 25 litres of Hel-X 13 can break down 170 g of fish food per day. Suitable for removing toxins such as ammonium, ammonia, nitrite and nitrate. The new Hel-X media are white in colour. They gradually turn brownish in colour so that the degree of colonisation is clearly visible. Hel-X 13 tower packings are particularly effective and cost-effective, and the medium does not need to be cleaned in combination with drum pre-separation.