Happens to all plants in few crops. Leavez will totally burn after 3 weeks flowering. Any one know what is it. This pics is 30 days veg. Ph test at 6.5 with promix hp. Feed every 2 days with 2 litres after transplant. Same nutrinet of GH for years, just got this problem last 5 months.. Keep moving 1 crop after another...Please help