Leaves curling up help

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
Attached Files:

• 
  a" style="margin: 0px; padding: 10px 10px 0px; overflow: hidden; zoom: 1; border-radius: 5px; font-family: Arial, TrebuchetMS, Helvetica, sans-serif; font-size: 14.6666669845581px; line-height: 18.7733345031738px; background: url(https://www.rollitup.org/styles/xpert/xenforo/gradients/category-23px-light.png) 50% 0% repeat-x rgb(255, 255, 255);">

i can't see pics

Looks like a heat problem. What's your day/night temperature exactly?