Heat stress and over watering me thinks, seems to be sorting itself out, opinions?

Just a quick check here, i'm not too worried really everything would seem to be sorting itself out but it's nice to have a second opinion

My grow journal is here.

They've had a fair bit of heat stress, my box has been above 30C and lamps have fell too close it seems at times (lost one plant that way i think), so i assume its between that and maybe over watering, although i thought i'd been pretty strict on my watering. No nutes have been used as of yet so it can't be an imbalance since they're 3 weeks old max...

Here are the pics that raised initial concern with my smaller plant:




And initial larger plant pics:




Here they are about a week later everything seems to be clearing up, but still curling away/down on the smaller plant.
Smaller plant recently:





Larger seems healthy to my untrained eye:





Here's comparison shot of both


Any input great appreciated! Cheers!

Anyone care to offer advice?

I will.
i have seen this in some of my plants. yeah, you were right.. it's heat stress. but like you also said it will work itself out. just dont over water and you will be just fine. if you dont have a fan you need to get one and they both look just fine. small problem, easy fix.

check the PH also, always good to keep an eye on it.

Cheers man, my PH seems about right, maybe slightly acidic on the run off i think, but i haven't checked that recently now because i'm assuming a lot of the nutes that come with the soil have run off or been used up now. Its hard to test my ph thought since i'm only using iodine i a test...

i dont know, it sitll could be your ph iam having a similar issue and havnt found an answer yet. i thought it was heat, but i have had my temps under very good control for a week now, and some new growth is starting to show the same signs. mine was also coupled with some upwards leaf curling in some of the larger leaves, that also pointed to heat, or Mag Def. Ive treated them with epsom twice now (foliar) and like i said that new growth is still showing it, though it doesnt start until a few days after the leaves have settled.

really eye those temps, but keep your ph really well monitored as well. you should be ph'n your water before and after you add nutes to it, and you should ph your soil run off each time as well.

Yeah man, well this grow box is a pain in the ass as mentions, hopefully picking up a wardrobe soon as and then i'll really start keeping an eye, atm it's just not feasible, i don't trust the box, the fans, and temp probe! Too many variables right now to pin one down. But it could very well be the Ph i guess as well, i've been using local scottish tap water left out for weeks (loads of bottles cycling) they should be good. Samples say about as Ph neutral as i get, but run off is a little too acidic i think... *shrugs* soon soon it'll be fine!