You can use the high N cal-mag, if your base nutrients are 2 part and allow you to reduce the nutrient's N dose as much as you add with the cal-mag. But it's better to just give the single needed additive (Ca or Mg) using epsom salts and gypsum vs. giving both at someone else's pre-set proportions. And foliar feeding has benefits of acting faster and not messing with your soil/media.
