In the marine aquarium, filter sacks and filter papers are used for the mechanical filtering in addition to the skimmers. So different mediums are mostly used in the force-flowed reactors: For the reduction of nitrate -and phosphate values, the phosphate adsorber is required in most of the aquariums which is usually reduced to iron base silicon -and phosphate values; they are brought to a near-nature area. Phosphate adsorber can either be hanged up in a reactor or in a filter sack. However biopellets and zeolite should be force-flowed and ensure a biological reduction of nitrate value. Best is that zeolite should be operated in a separate zeolite filter. With activated carbon, specific poisons and nettle toxins are bonded in the aquarium.