If you look at the API instruction manual under "Nitrate" test and just above where the actual instructions are, you will see a paragraph regarding dividing by 4.4. This means that if you compare the API results to a test that tests Nitrate as NO3-N (total nitrate-nitrogen), you will need to divide by 4.4 to accurately compare the tests. From what I understand, when we talk about "nitrates", it's NO3, therefore the result you get from API (in this case its 20ppm) is your nitrate result.
Yes, it is confusing.
Yes it is.
From my science classes and engineering experience one of the most important things to specify when writing reports or when reading reports is the units being used. Even the simple F=MA is actually F=kMA where k is the conversion factor for the units being used.
Back to aquariums nitrate-total or nitrate-nitrogen are both perfectly acceptable means of measuring the concentration of nitrate ions. And most test kits measure nitrate total. But to be precisely correct one must specify which units are being used. What makes it more confusing is both are ppm nitrates. Unlike alk which had degrees, ppm. meg/l and what have ya.
my .02
Last edited: