Purple Lemonade

A lot of fan leaves yellowing with brown spots. Lower ones are going crispy and curling upward before dying altogether. Tried adding more potassium n cal mag but no good so think I'll flush after this week to correct what might be nuts burn. Very strange because the gelato I'm growing at the exact same time and on the exact same nute schedule is not showing any obvious signs of nutrient deficiency or overdose. Will have to see but at least it's flowering quite strong at the moment.