The Salifert Ammonia Profi-Test Kit rapidly and accurately measures total ammonia and ammonium levels and can detect as low as 0.5ppm. This test kit is sufficient for up to 50 tests and can easily identify any issues resulting from an excessive biological load to the system, which would disrupt the process of nitrification into nitrite, nitrate, and nitrogen gas. Instructions for use: add 1ml of water to the test vial, followed by 6 drops of NH3-1 then NH3-2 (careful--NH3-2 contains mercury salts). Swirl gently for 5 seconds after each, then let sit for 5 minutes. Compare the test to the color chart, and take the results in mg/L total ammonia (NH3 + NH4+).