Cirax is a biological filter medium which creates the perfect colonisation conditions for useful bacteria, due to its large, highly porous surface. JUWEL Cirax are highly porous ceramic-based pellets which, due to their extremely large surface area, create the perfect environment fulfilled the bacteria. In your JUWEL filter, Cirax helps to ensure excellent water quality. Using a special basket, tailored to the size of your JUWEL filter, makes it easy to use, whilst the optimised filling quantity means a long service life of up to a year.