I have absolutely NO idea how the idea of Ca deficiency came into play here! :wtf:

Purple petioles and stems are signs of Sulfur deficiency, low temps, or even simply related to the strain.

You need a better fertilizer either way. The MG you are using isn't appropriate for any cannabis life stage, and your dosage rates are no good anyway.

You also need to check the pH of your soil runoff to eliminate lockout.

Without a better pic that shows more of the plant, plus info on your growing conditions (look in the sticky!!!) all this is just guessing.