Low range: 0.2 - 10 mg/L (ppm) as nitrate.
Medium range: 2 - 100 mg/L (ppm) as nitrate.

Procedure for both ranges:

1. Fill test vial with 1mL of water.
2. Add 1 level scoop of NO3-1 powder (compress this powder against the inner side of the powder container).
3. Add 1 level scoop of NO3-2 powder and swirl gently (do NOT shake) for 30 seconds.
4. Let it stand for 3 minutes.
5. 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 10mg/L nitrate then it might be better to compare colors as shown for the low range (see below).
   
   Low Range:
   
   If the medium range color comparison procedure gave a reading lower than 10mg/L then you can use the low range prodecure. This will increase the accuracy.
   
   The color for the low range procedure has to be compared by looking through the SIDE of the test vial.
   
   The white part of the color chart has to be held firmly against the opposite side of the test vial. Use diffuse daylight when comparing colors.
   
   The color is, by looking through the side, amplified by approximately 10 fold. For this reason you have to divide the color chart values by 10. For example 2 will become 0.2 and 50 will become 5.