Bio-cartridges with extractable filter pads offer the best colonisation conditions for the important purification bacteria.
3D-active carbon cartridges, on the other hand, remove unwanted toxins and should be used especially after medical treatment or initial set up of the aquarium.
Included with each filter pack is always at least 1 large biofilter cartridge with 240 cm3 volume. Depending on the model, also included are two or three extra cartridges.