Nitrates build up in an aquarium with insufficient oxygen or improper denitrification (a process of biological filtration). Nitrate retards coral growth and promotes harmful algae blooms. Salifert's Nitrate Test Kit is the height of accuracy and precision, and will not be affected by amines, which in many nitrate tests can cause results to appear much lower than they are.
Fill test vial with 1 ml of aquarium water
Add 1 level scoop of NO3-1 powder (compress this powder against the inner side of the powder container)
Add 1 level scoop of NO3-2 powder and swirl gently (do NOT shake) for 30 seconds.
Let stand for 3 minutes.
For color comparison: Medium Range:Place the test vial on the white part of the color chart and compare colors looking from the top. Use diffuse daylight when comparing colors. If the color corresponds to a value lower than 10 mg/L nitrate, then accuracy will be increased if you compare colors as shown for the low range (see below). Low range: The color for the low range procedure has to be compared by looking through the SIDE of the test vial. Hold the white part of the color chart firmly against the opposite side of the test vial. Use diffuse daylight when comparing colors. Looking through the side amplifies the color approximately 10 fold, so divide the color chart values by 10. For example 2 will become 0.2 and 50 will become 5.