Tetra test nitrite kits are reliable, accurate and use professionally designed methods to determine if your tank water is safe for your fish Toxic nitrite is broken down into non-toxic nitrate during the nitrate cycle’s second stage of decomposition by bacteria, such as those from the nitrospira genus. Nitrite is a nitrogen compound that is formed as a result of decomposition processes in the aquarium. High levels of this indicate that there is a problem with the biological filter system. The nitrite content should ideally be less than 0.3 mg/l and thus not measurable. The aquarium water must be checked weekly to detect dangerous nitrite concentrations early. Contents: - 2 x 10ml test reagent Test vial Colour Scale Chart Instructions and Recommendations How To Use As a liquid test kit.