The Nitratereductor NR Blue is an anaerobic biological reactor for removing nitrates from salt and fresh water aquaria. It has an approx. 1.25gal. volume and an internal circulation pump. The NR Blue has a flow rate of approx. 0.25 – 1 gph. In the absence of oxygen, bacteria metabolize nitrate. Denimar powder or Deniballs are used as an organic energy source. The NR Blue is a closed system that can be integrated into a filter system, or installed as a standalone system. Deniballs and Bactoballs are included. Rated for up to 270 gal. aquaria.