A nitrogen supplement for the planted aquarium, provides nitrogen in two forms. 250ml treats 2000-20000 litres. Nitrogen is one of the main three macro nutrients (nitrogen, phosphorous and potassium) required by plants and can often become the limiting factor to growth in a flourishing system. Flourish Nitrogen is a concentrated (15000mg/l) blend of nitrogen sources. It provides nitrogen in both the nitrate form and the plant preferred ammonium form. However no free ammonia is released because the ammonium in flourish nitrogen is complexed and unavailable until utilized by the plants. Flourish Nitrogen also provides nitrate for those plants that can readily utilize nitrate as well. For maximum benefit use with flourish phosphorous and potassium. Flourish nitrogen is safe for invertebrates such as shrimp.