Sera Nitrite Test for the xact determination of the nitrite content (NO2) in fresh and marine water. The test ist sufficient for approx. 75 test. Useful bacteria convert ammonium to nitrate via nitrite. Nitrite, the intermediate of the pollutant breakdown, is a strong blood poison which often enrichs in newly set-up aquariums. By using of the sera nitrite-test it is easy to determine the level of toxic nitrite. In a aquarium with a good working biological filter, the nitrite level should be 0. Sera Nitrite Test+ monitor the nitrite level in aquariums and garden ponds according to scientific standards+ for new aquarium setups and after cleaning the filter+ a nitrite concentration that is too high is fatal for fish+ complete kit with vial, syringe, and evaluation chart for precise water analysis+ with a readily understandable video tutorial for easy use+ for approx. 75 single tests