If a plant has cal and mag and phosphorus def how do you correct these

Hard to answer if you dont tell us what you're growing in and what nutes

Says soil medium in your diary but your using coco bloom? Canna a b what? Terra ? Coco? Hard to answer when we dont know whats what. If your in soil not soiless like coco or peat, then you should never have a cal/mg issue. If you do it would be to lockout where their just not taking those elements up.