Marina Slim Filter Carbon Plus Ceramic Cartridge, 9-count 3 3-filter packs of Bio-Carb carbon filter cartridges Replacement cartridges for all 3 Marina Slim Filter Models Ideal filtration media for maintaining clean, healthy water in tropical aquariums Contains activated carbon and Ceramitek for optimum filtration and a healthy aquarium The activated carbon effectively removes pollutants and odours, while the Ceramitek, a highly porous ceramic biological filter medium, optimizes biological filtration