What is the difference between nitrate ion and nitrate-nitrogen readings?
Measurement of the various nitrogen compounds (ammonia, nitrite and nitrate) can cause some confusion regarding units of measure. What is being measured must be determined. For example, does a nitrate test measure the parts per million of the nitrate ion, one nitrogen and three oxygen atoms, or just the nitrogen alone. The latter, commonly used for scientific work, has an obvious advantage in monitoring the nitrification cycle in aquariums. The progression of the nitrogen in an aquarium where 1 ppm of ammonia-nitrogen is added ends up as either 1 ppm nitrate-nitrogen or 4.4 ppm nitrate ion. Both are the same concentration, but the first is easier to follow.
