Just found out some information. The API test kit is not the best out there for testing. They are other brands (Salifest, Hanna, etc.) which are better. Anyways please go to API website and click:
Welcome to API Fishcare: SALTWATER MASTER TEST KIT
Go to Salwater Master Test Kit Instructions and click Learn More. Here is what they say for Nitrate:
"This test kit reads total nitrate
-) level in parts per million (ppm
) which are equivalent to milligrams per liter (mg
/L) from 0 ppm
to 160 ppm
, in either fresh or saltwater aquariums. This kit includes two Nitrate
Test Color Charts — one for freshwater aquariums, and one for saltwater aquariums — so be sure to use the correct chart for your type of aquarium when interpreting test results. The Freshwater Nitrate
Test Color Chart is the appropriate chart to use for testing freshwater aquariums to which salt has been added. This test kit measures nitrate
ion or “total nitrate
.” Other nitrate test kits that measure “nitrate-nitrogen” (NO3-N) will give readings 4.4 times LESS than this test kit."
When I take my 30ppm of Nitrate and divide it by 4.4 I get 6.8ppm which is less than 10ppm. With the amount of water changes I have done this makes sense. I read another post where API was compared to Salifest and the results were similar when you do the calculation.
Please read instruction from API regarding Nitrite and Nitrate testing. This would be very helpful regarding your test results if using this brand.