leaf sides folding upwards

hi please help!!!!

i have following setup:

space:4x4 feet
vent: 260m³/h
humidity: N/A
distance of light to plant 80cm
2x800w Mh bulbs
9 Pots/plants
1week since sprouth
strain: sensi seed jack flash and feminized mix
outrun water ph: 6.3-6.8
i have fert them too urly i think but not very much fert
soil mix: light mix, perlite 1/3,cocofiber, vermiculite
my question is why do the edges of the leafes fold upwards like in photos?? id it because of the heat, humidity or becaus nutrient deficient or other way oround?
thank u

1600 watts?! On seedlings?! Damned the torpedos man, go for the gusto. I'd say they are trying to protect themselves from the light, flouro's would be fine for a couple more weeks yet... but idunno, nice setup though

When that happened in my first grow, it ended up being a Mag deficiency. The folding is called 'praying for mag' if its a correct diagnosis, but the cause could be a couple things. Might be a nute lockout due to a ph imbalance, or just not enough in the soil/nutes. What is your ph before you water (saw runoff but not starting numbers in your op). I see your still in light mix, and i used some as well which i think may have had something to do with my mag issue (though i was using jiffy).

If i had any advice (and iam not saying i do) i would say give her a small flush (maybe twice the container's size in water) then treat the ones suffering with a water solution (ph treated to around 6.8.) with around 3ml of CalMag per gal. Epsom salt is another viable option for this, around a tablespoon mixed per gal (its best to pre mix the salt with some warm water to speed up the dissolving).

Iam no pro, but if it IS a mag def, those are the steps i took to fix it when it happened to me. Of course, it could be as simple as curling due to heat stress. The plant is unable to move water through its system fast enough to balance its transpiration, so it folds it's leaves edges to attempt to block the heat and hold more moisture in, if i understand it correctly.

thank u.
I read on other threat it could be magnesium, i flushed the one thats more folded. I mesure my ph everytime before i water its never more than 6.8
last night i sprayed them with piranha from an. that as magnesium in it. As i woke up and looked it openet a lot more. I`m planing to move them to a bigger pot end of week and there i will use some guano mix. i hope i will see the diff.