API Nitrate Test Kit can detect high nitrate levels from 0-160 ppm (mg/L) in freshwater and saltwater that may lead to algae growth and poor fish health. Nitrate is produced in the aquarium by the biological filter. Beneficial bacteria convert toxic ammonia and nitrite into nitrate. High levels of nitrate indicates a build-up of fish waste and organic compounds resulting in poor water quality and contributing to the likelihood of fish diseases. With API Nitrate Test Kit, you can easily and accurately measure the nitrate level and take steps to remove it. This kit includes: 2 liquid droppers, easy to read instructions on how to test and correct water conditions, 2 color charts, and a glass test tube. 90 tests per kit. Shipping weight: 1/3 lb.