Actually the cal/mag in hard water is not readily usable by plants, even if you have hard water with cal/mag in it you still may need to supplement these nutrients with cal/mag in a form that can actually be absorbed and used by plants. Carbs and sugars actually feed the benefical bacteria that aid in assimilating the non usable minerals in water/soil into forms that plants can use.It all depends on how much calcium and magnesium is in your well water. You only need CaMg if you have very soft water... or if you are growing in coco. Adding molasses or other carbs/sugars isn't extremely important. It will grow "plumper" buds. Its really only important when blooming.