The Salifert Freshwater Nitrite Test Kit is a reliable and accurate way to test nitrite levels in your aquarium. Nitrites are the most dangerous compounds in the nitrogen cycle and can be fatal to fish, so it's important to regularly test for them. With the kit's easy-to-follow instructions, simply add 2ml of water to the test vial, then measure and compare the nitrite levels against the color chart. For ideal conditions, a level of not higher than 0.1 mg/L is recommended. Keep your fish safe and healthy with the Salifert Freshwater Nitrite Test Kit.