thanks this will help. You hav another link for EI target ppm. the Calculator is useful but I'll need that information to work with it.
the last lineNot only a target ppm tho you can choose show the result of your dose of 1 gram of KNO3 for example and see what that brings its to. Since you know the target of 10-20 ppm Nitrates you do the math and figure out you need ~3g of KNO3 to meet that requirement.
The calculator makes it pretty easy for you so what else would you need to know?