Nitrite is a toxic nitrogen compound, produced when there is a disturbed bacterial balance or when the water is rewatered. The test displays the exact nitrite content of the water. Laboratory comparison system to compensate for the water's own coloring: fill the test tubes with water to be tested, add the reagents to a test tube, place the test tubes in the test block, read the values on the color chart. Use: for new freshwater tanks: every day for 3 weeks. For new seawater tanks: once a week. Included in delivery: 1 Nitrite test for approx. 50 measurements, 2 reagents, 2 glass test tubes with screw cap, syringe, comparator and colour chart. Reagent refills available separately.