The top-class liquid filter medium Liquid biofilter medium Contains purification bacteria For crystal clear water Due to the purification bacteria it includes, sera pond bio nitrivec, a sera biotechnology product, breaks down ammonium and nitrite effectively, quickly and in a natural way. The included mineral volcanic rock removes pollutants, effectively binds cloudiness and provides settling space for the purification bacteria. The volcanic rock also contains calcium, potassium and magnesium - indispensable minerals that are continuously consumed in a pond. For healthy, clear and biologically active water. Allows adding fish already after 24 hours!