Nyos Nitrate v Hanna Nitrate HI781 - Confusing Results

Mark Lang

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Sep 21, 2018
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I have confusing results when comparing my Nyos nitrate test to my Hanna nitrate test and need some help sorting out what is happening.

Nyos regularly gives me a <1ppm reading. (The vial is barely perceptible yellow).
Hanna HI781 is giving me a >5 ppm reading. (The cuvette was BRIGHT pink).

Nyos has been giving me this result for about 5 months. Because Nyos regularly gives me a result of less than one, I purchased the Hanna low range to try to get a more precise reading. I'm not sure how to sort out which is accurate.

If Hanna is correct how do I understand why Nyos isn't reacting to the reagents and vice versa.

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Apr 12, 2019
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Assuming the hanna was performed perfectly, I would be it to be much more accurate. Nitrate tests (and many kits in general) are not accurate enough to give you the exact reading. A few ppm difference is likely what you would encounter with any test kit.

You may want to do the dilution to get a higher hanna reader to see what it says.

I will say that the nyos nitrate is an odd one for me. It always gives me a color that is not really like that on the color card.

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