Ahh.... flowering prob plz help

So my plants were looking great for the first 5 weeks of flowering and now something has come up. I am starting to notice that the leaves are turning yellow at the tips and are curling to the left. two of my three plants seem to have less sever signs of this, but all are showing the issue. The other one seems to be stunted by this issue as i have seen no noticeable growth in the past week any idea of what could be the issue here. Im using a fertilizer that is 16-55-15 but only giving them half a recommended dose for a plant of there size could this be the issue?

the leaves turning yellow at the tips could justbe a sign of too much heat, whats ur temps at the tops of your plants?

and leaves curling to the left? first, are u sure they arent just bending towards the light, and secondly, it could be overwatering.

hope this helps