Nitrate / Nitrate-Nitrogen . . . can someone please explain

D

diggozo

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Quote from my Nitrate Test Kit Packet. . .

"The ******" NO3 Kit measures total nitrate ion (NO3) concentration. To obtain the value for Nitrate-Nitrogen concentration in mg/l, the value obtained with the kit should be divided by 4.4".

Can someone please explain in simple terms the why and the wherefore of a NO3N reading and why one would want it.
 
Nitrate is the final stage of waste breakdown in the aquarium. Ammonia is consumed by bacteria that produce nitrIte as waste. Different bacteria consume the nitrIte and produce nitrAtes as a waste product.

Nitrates are important to control for a number of reasons, depending on the setup. In an unplanted aquarium, nitrate levels can be used to roughly monitor the levels of other toxins that are not easily measured. While nitrates are not specifically harmful to fish at moderate to high levels, long term exposure to them can cause problems, and of course the other toxins in high levels can certainly compromise fish health.

In planted tank, nitrates are a food source for plants. Maintaining them within a target range means the plants have a stable food source.
 
To expand on OG's good comments and hopefully address part of your original question, we are dealing with one dissolved gas and three nitrogen ions: NH3/NH4, NO2, NO3. They all have different molecular weights. Common test kits tend to report the total ion, but when you attempt a material balance with those figures, it does not work - 1 ppm of ammonia or ammonium does not result in 1 ppm of nitrite and that in turn does not result in 1 ppm nitrate - because each of those materials has only the one nitrogen atom, but varying other materials (3 or 4 hydrogens, or 2 or 3 oxygens). Chemically it is easier to work with only the nitrogen, reporting only total ammonia nitrogen (TAN), nitrite-nitrogen, and nitrate-nitrogen. Using those terms, 1 ppm ammonia-nitrogen does result in 1 ppm nitrite-nitrogen and that in turn results in 1 ppm nitrate-nitrogen. Note that these are not necessarily different tests, ony different reporting scales. The 4.4 is the conversion factor for nitrate to nitrate-nitrogen. The comparable factor for the nitrite ion to nitrite-nitrogen is 3.3.

HTH
 
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