LaMotte method to test nitrate-nitrogen

The LaMotte nitrate-nitrogen test measures how much nitrate is in water. To do the test, you fill a small test tube with your water sample. Then, you add a special powder or tablet that reacts with nitrate. After shaking and waiting a few minutes, the water changes colour. You compare this colour to a chart that shows how much nitrate is present. The result is shown in parts per million (ppm).