API/Salifert vs NYOS

[Anthrax15]

NYOS reading 10ppm for Nitrates. API and Salifert reading closer to 30-40ppm based off coloration. Trust the two or go with the NYOS?

 

[P-Dub]

Nyos and Salifert are both relatively accurate. The tough part is looking at the results under as true a white light as possible. I would go with somewhere in between those two. I would also test at least twice on both to mitigate human error.

 

[Dan_P]

NYOS reading 10ppm for Nitrates. API and Salifert reading closer to 30-40ppm based off coloration. Trust the two or go with the NYOS?

This is a tough call to make. You really need to have a standard, that is a known concentration of nitrate, to determine which test kit is closest to the truth. Every test kit can vary from manufacturing batch to batch. Except for tests like Hanna and Hach, no test kit provides you with any information on accuracy and precision. It is really a crap shoot.

Without a standard, all you can reasonably do is to average the results.