I can't personally vouch for the General Hydro, however I know many people that use it. To my knowledge it shouldn't be an issue. My biggest recommendation is let the plant tell you what it needs, as I have seen far to many new growers (myself included) over feed plants and cause worse issues then what would have occurred if we didn't add any.
View attachment 3675246
Charts like this can help tell you what your plant needs or doesn't need. Pictures of plants are always helpful as well, but please shut off LED of HPS lights before taking photos!