The spots you can fix it if you add cal mag. If you are using distilled water you have to add a cal mag supplement no matter what. I'm not sure about the yellow. When I learned my lesson about distilled water and cal mag being necessary from the get go I still had a nice green tone to the leaves. Though if I were to guess I would think it might be PH related. distilled water doesn't give accurate PH readings with a meter. After adding a cal mag supp you can get a true reading. Also i seem to remember that pro mix hp has alot of peat which has high acidity on its own.