Nitrite (NO) is the intermediate stage of the aerobic nitrification and is highly toxic for fish and invertebrates. A too high concentration of nitrite impedes the oxygen transport in the blood and severely restricts celluar respiration. With this test, the nitrite content can be accurately determined from 0.01 to 2 mg/l with the finely tuned colour chart.Nitrate (NO) is the final stage of the aerobic nitrification and impairs the well being of fish and invertebrates to a lesser degree. But high nitrate concentrations can accelerate algae growth and impede the growth of certain corrals. Oxygen shortage in the aquarium may cause the reduction of nitrate to poisonous nitrite.With the Tropic Marin Nitrite/Nitrate-Test the nitrite and nitrate concentrations can be determined using a finely-tuned colour chart which has a range of concentrations for nitrite of between 0 - 2 ppm and for nitrate of between 0 - 50 ppm.Tropic Marin NO2/NO3 Test+ measurement range: NO2 0 - 2,0 mg/l (ppm)+ measu