I have 3 plants and they are all looking the same. The humidy level is 40% and 81 degrees F. Some of the leaves look healthy others look curled in and dry. I water them about 2 times a week and the lights are LED.
Its hard to see with the purple light you have on it but you say you water it 2 times a week ? That may be your problem right there They look rather new but large still in solo cups so I'd suggest repotting and less water . Maybe like once a week with a spray bottle until they show sign of improvement I maybe all wrong , can't really make out much after a second look Sent from my SM-G930T using Tapatalk
Heat stress u need some fans in that room. Provides fresh air! U also got other things going on. Take a pic when lights out with ur cams flash. Blurple hurts us helping. Pics if whole plant where we can see even the soil Sent from my SM-G935T using Grasscity Forum mobile app
Sure looks like heat stress like these guys said above me. Being warm AND down at 40% RH, intense light can stress the plant. The leaves canoe to basically shield themselves from light. Even lower powered lights can do it if the ambient temp is high while the air is dry. Even just spraying and keeping the room humid will help, and can help bring temps down a little. IME vegging plants LOVE warm and humid. I always get healthier, more vigorous plants when I "greenhouse" them young. I might take them out of those Rubbermaids too, let the air flow over them better. Will let light surround them better, instead of a blackhole sucking light outta the room. Air flow around them, moving them, even slightly, also strengthens the stalks. I always make sure any room I flash up has plenty of oscillating fan power. Those leaves are extreme so you might not get full recovery, but they should become more pliable if you can get the humidity up. A non-purple photo would be best if you can do that too. Right now I can't tell if it's just the light or you have red/purple leaf stems for example.
If you are in veg, your humidity needs to be higher. You’ll run into problems in veg at low humidity. If you continue to grow them at 40% humidity, you’ll need to lower the concentration of your new translation. If the leaves are unable to pull moisture from the air through the stomata, they will feed heavier from the roots to get what they need. If your nutrient solution is too strong, you will burn the shit out of them. Feed weak and feed often. I do agree with some of the other comments. That does look like heat stress, but the low humidity is not helping you. Sent from the grow room using my fingers.