Biological filtration is absolutely necessary in saltwater aquariums for converting Ammonia and Nitrite into less dangerous Nitrate.

Even so Nitrate accumulate in water and at high concentration can be quite dangerous.
A solution for eliminating or at least decreasing the Nitrate level is not so easy: in fact bacteria which can transform Nitrates can survive only in anaerobic environments, which are quite difficult to recreate.
RWNO3 Nitrate Filters contain in the upper section a special material, which has the capability to remove oxygen from incoming water.

In this way the lower section of the filter becomes automatically anaerobic and etherotrophic bacteria can take place and grow into colonies.

For getting the best result, water flow through the filter must be very slow, better if "drop by drop".
RWNO3 Nitrate Filters are provided with a circulation pump and with a check valve for flow regulation.
Nitrate levels must be periodically checked at the filter outlet: if traces of Nitrate are found, the filter material should be replaced.

RWNO3 Nitrate Filters can be placed both internally/externally to the sump and are available in 3 models:

• RWNO3/130/400 - Ø 130 mm - total height 42 cm - for aquariums up to 400 litres
• RWNO3/130/500 - Ø 130 mm - total height 52 cm - for aquariums up to 600 litres
• RWNO3/130/600 - Ø 130 mm - total height 62 cm - for aquariums up to 800 litres