Flourish Nitrogen, 2 L / 67.6 fl. oz. Nitrogen supplement for the planted aquarium A concentrated blend of nitrogen sources provided in both the nitrate form and plant preferred ammonium form Will not release free ammonia because ammonium in Flourish Nitrogen is complexed and unavailable until utilized by plants Nitrogen is one of the three main macro nutrients required by plants and can often become the limiting factor to growth in a flourishing system 250 milliliters treats 500 to 5000 US gallons