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Re: Nitrates

Shireen quizzed:

What is your definition of the word "nitrate" as printed
on the instruction sheets of nitrate test kits?

Multiple choice version:
Nitrate is
   A) NO3
   B) NO3-N (nitrate nitrogen)

Essay version:
what does NO3-N mean?

It would be useful to add the definitions of NO3 and NO3-N to
some FAQs, and explain somewhere that when people commonly
talk about nitrates, or refer to it as NO3, they're really talking about
NO3-N. It's a very confusing issue.

The shorthand for nitrate is NO3. That means it's made of one element of nitrogen (N) and three elements of oxygen (O). If you want to get technical with it, you can add a minus sign to the end (NO3-) to represent the overall negative electrical charge nitrate has. When folks talk about nitrate, NO3 is what they are referring to.

Nitrate-nitrogen (NO3-N) is basically just a way of saying "nitrogen that comes from nitrate." In other words, it just refers to the nitrogen part of the nitrate molecule. A value for ppm nitrate-nitrogen can be converted to ppm nitrate by multiplying by 4.4. For example, my Hach test kit gives results as nitrate-nitrogen. Earlier today, I tested one of my tanks and the reading was 0.8ppm nitrate-nitrogen. That means that the tank contained 3.5ppm nitrate (0.8 x 4.4 = 3.5). The familiar guideline of 5 to 10ppm nitrate is the equivalent of 1.14 to 2.27ppm nitrate-nitrogen.

Hope it helps.
Chuck Huffine
Knoxville, Tennessee