Seachem Flourish Nitrogen. Nitrogen is one of the main three macro nutrients (nitrogen, phosphorus, potassium: NPK) required by plants and can often become the limiting factor to growth in a flourishing system. Flourish Nitrogen™ is a concentrated (15,000 mg/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. Ammonium becomes available after conversion of urea (carbamide). Flourish Nitrogen™ also provides nitrate for those plants that can readily utilize nitrate as well. For maximum benefit, use with Flourish Phosphorus™ and Flourish Potassium™. Flourish Nitrogen™ is safe for invertebrates such as shrimp.