A filter for reducing the nitrate concentration in aquaria up to 400 litres. (c.100 gal) The Nitratreductor 400 is a completely sealed biological filter. It is operated at a very low flow rate so that an oxygen free environment is created wherein naturally occurring bacteria reduce nitrate to harmless nitrogen gas. The filter can be installed in almost any position, inside or outside the aquarium or the cabinet. For the water flow, we recommend the Dosing pump SP 3000. After maturing the filter can keep the nitrate concentration in a normally loaded aquarium up to 400 litres at a very low level. The filter medium - Deniballs - is consumed and will require replacement in 9 to 12 months dependant on load. For optimum control we recommend the filter be used in conjunction with an Aqua Medic mV (Redox, ORP) controller. The filter is already equipped to accept our pressurised electrode. Dimensions (without electrode) : 14.4 x 10 x 37 cm c. 5.8"x 4" x 14.5" ( L x W x H) Assessories : Denimar powder and deniballs to feed the anaerobic bacteria Pressure proof Redox (ORP) probe with screw connection PG13.5 Dosing pump SP 3000