Phosphor or Potassium?

Phosphorus lockout causes that purple on the leaves. Also light stress from LEDs can do that as well. There isn't much you can do for it this late into flower. I would Flush her with PHed water and 1/2 strength fertilizer so she doesn't go further into lockout.

I can see it suffer of nutrient burn because your soil must be too rich. But for your phosphor deficience the problem can be your soil PH if it is above 7 phosphor can't be absorb by your plant. So try to check it and solve it as soon as you can. Good luck

Hello in my opinion it a phospor deficience if it was potassium you will have brown spot with yellowing and dry leaves rolling. So phosphor deficience. Good luck

Also I used my own living soil mix, but they showing signs of to much nitrogen. Leaves looking on the top dark green and the bottom leaves starting to fade out. My last run was perfect with the same ingredients, but this time they showing all some signs of Defs and that's a bit to early for me.