karenjo,
Are you following these instructions to the letter ?
You only use 1 ml of tankwater on the medium range test, and do not add the NO3-2 reagent.
You use 10 ml of tankwater on the low range test, and you only use the NO3-2 liquid reagent when doing this low-range test.
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Medium range procedure:
1] Fill test tube with 1 ml of water.
2] Add 1 level scoop NO3-1.
3] Add 1 level scoop NO3-3 (NO3-2 is omitted in this procedure) and swirl gently for 30 seconds.
4] Let it stand for 3 mintues.
5] Place the test tube on a white part of the color chart and compare colors looking from the top.
If the color corresponds to a value significantly lower than
10 mg/L try using the low range procedure to obtain a
better resolved value.
Low range procedure:
1] fill test tube with 10 ml of water.
2] Add 1 level scoop NO3-1.
3] Add 1 drop of NO3-2 reagent.
4] Add 1 level scoop NO3-3 and swirl gently for 30
seconds.
5] Let it stand for 3 minutes.
6] Place the test tube on a white part of the color chart and compare colors looking from the top.
Divide the values on the chart by 10!
Note: A reading, after division, of 10 mg/L (ppm) could
imply that the value is higher. Use medium range
procedure in such cases.
Values on the chart are in mg/L or ppm NO3.