In weed groups, the post "whats wrong with my plant" always has advise to use calmag. So, my question is, out of all the micro and macro nutrients, why did someone decide to join calcium and magnesium? What if you only need mag? Or only need magnesium? What then? Why isn't there copper/iron? Or manganese/sulfur? I'm not clear on the logic of this product? Does anyone know why this stuff has a religious following?