Leaves curling up

My plants are critical kush an pineapple express day 38 in bud i use coco perlite mix duth mast gold nutes cal mag add 2.7 flower ph 5.8 to 6 ec 1.8 to 2 temp 28 deg cel and so everything looks great n green but the leaves r curling up any ideas

It's just a bit of heat stress. Try getting more airflow between the light and canopy, that should help.