Activated carbon filter for Cata CG5-T600 range hood. Range hood in recirculation mode: In this mode, the extracted air passes through the grease filters and also passes through an activated carbon filter, which somewhat filters unpleasant odors and vapors, and then the cleaned air is returned to the kitchen air. In this case, the capacity, depending on the state of the carbon filter (wear and tear), is approx. It drops to 60-80%. This mode of operation is only recommended if there is no outlet. Activated carbon filters must be replaced every 3-6 months, depending on use.