First Green Crack and Bio-heaven test

The plants are growing very well even if the temperature gets really high sometimes, slight heat stress (at 38°C it's normal) I quickly responded with AC to keep things cooler. To help manage the thermal load i also switched the light cycle to 6/2 cycles 3 times a day. The bio-heaven-fed plant seems to pull ahead a little but it's way too soon to draw conclusions. I plan to start LST after the 5th node appears which is hope happens during early/mid week 3 I am already bending the leaves a little to bring more lights to the lower nodes After stabilizing the temperature i took a look at a VPD chart ( http://i.imgur.com/HBnT439.png ) i noticed my humidity caused the leaf curling problem I raised the humidty to 70+% and try yo keep it there to keep the VPD below 9