For the reduction of nitrate -and phosphate values, phosphate adsorber is required in most of the aquariums which usually reduced on iron-base the silicon -and phosphate values. 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.