If they are turning yellow and curling and are slightly wrinkeled then it's heat stress in which case you need to back your light up and spray your foliar feed during dark hours only, foliar feeding is kinda hard to do. Also, the problem could very well be a Magnesium defieciency, if the new leaves curl without any yellowing use epsom salts, the problem should appear to be fixed within four new node growths. My grow has examples of light stress on my largest plant, follow the link in my sig and you'll see what it looks like