From what I have read, API reads one thing and others read another for nitrates. I have not been able to figure our which is the actual number we should be looking for.
This test kit reads total nitrate (NO3
-)level in parts per million...in saltwater aquariums. This test kit measures nitrate as nitrate ion or "total nitrate". Other kits that measure "nitrate-nitrogen" (NO3
-N) will give readings 4.4 times LESS than this test kit.
I'm not sure that means you should divide it by 4 (or 4.4) Or if people with kits like RedSea should be multiplying their readings by 4.4. Seems that its an apples and oranges thing, but sure would like a definitive answer.