Well, sorry guys, but after reviewing the calculator and its results, I think it (kind of) correct. The problem here is that doesn't make sense to use "grams" for a liquid mix like Flourish Nitrogen, therefore you should use ml for liquids and grams or milligrams for solids as Mihai wrote above, otherwise the calculator is going to give unexpected results.
What instead we could do, is to remove the "solid" measurements when a liquid mix is selected, and vice-versa. Do you all agree on that? If so, I could fix it that way.
Thanks.