The filter medium Carbax sets new standards in aquarium filtration with activated carbon. Carbax is a highly effective, coal-based granular activated carbon specifically designed for the purification and decolorization of water-based liquids. Unlike common carbon filter media, Carbax fully activates the entire activated carbon granule, not just the surface. As a result, Carbax binds discolorations, odor substances, and toxic compounds particularly quickly and sustainably, ensuring crystal-clear water in your aquarium.