Leaves curling up

I'm on day 6 of my first grow with 6 platinum og kush growing in fox farm ocean forest soil in 5 gallon containers. We are only watering them every 3 days no nutes added yet. We are growing in a 3x3 tent with a 400w hps light on 24/0. They seem to be growing about 1/2 an inch every day by my measurements. I just noticed today that the leaves on 2 plants are starting to curl up no brown spots or anything on them. Is this normal or should I be worried? We are getting a temperature gauge this weekend and another fan to put inside to have more circulation. I do not know the ph of my water we will need to get the stuff for that also this weekend. I did the hand test to see if the light was too close and it seems like it is at a good distance from the plants. Any help would be greatly appreciated since I'm new to this.

It looks like a little heat stress from the hps. She looks ready for 1/4 strength nutrients. Get your temperature guage, and add more circulation for sure. Looking good!

Thanks for the help! You think it's ok to start adding nutes this early everything I've read says wait 2 weeks with the ocean forest soil? Thanks again for the advise!

Use a cap full of nutes per gallon of water,ph'ing after you've mixed,and add another couple of fans,or one big one.It looks like just a bit of heat stress,if it was n toxicity the leaf would be really dark green.Best of luck

Yes I start 1/4 nutrient watering after 30 days in ffof.

Thanks for all the help! I raised my light last night and started 1/4 botanicare kind nutrients the base and the grow today.