Burnt Leafs ?

Hello guys, first time grower

I have 2 automated feminized northern light and 3 feminized aurora indica, all 4 weeks old from germination.
All planted in 0.5 liter pots and then moved to 13 liter, grown outdoors. Soil is a mix with a bit of compost.
Average temp. is around 28-30 Celsius for most of the day.
I water them from a local spring, 1 liter each 3 times a week (watching the ground if its dry or not when i press against it). Adding nutrients every 3rd watering.

In just 24hours after a day of intense heat and sun I noticed burnt leafs on some of them. 3 days later here are the pics:






Some look better than before, but just to make sure its because of the intense heat?
What should I do the next time it happens and how to manage the shown burnt leafs now?

Thanks!

I'm not sure it's heat but the first pic has the look of a bug issue as the holes in the leaves looks like somethings has been eating your plants

Second, it could be a deficiency, maybe cal-mag...but your spring water shouldn't need it unless it;s very soft water

I don't see signs of heat stress either.

I don't see anything involved with heat. Looks like bugs according to first picture. Good luck with your grow.

Well it had bug issues and then I sprayed it and it stopped the biting. A week after that came the yellow burnt look.

The first pic definitely looks like bugs... mites, thrips, aphids or the like? Is anything jumping in the soil when you water? It could be babies in the soil. The second and third look like a deficiency. If you're absolutely sure the bugs or gone, it could just be residual damage from them sucking on the plant. Keep checking the undersides of leaves and nodes close to the stem for hard to see bugs and give it a few days to see how it goes. Check again if the damage keeps getting worse.

Ok I'll watch over it for a couple more days
I'm sure there are lots of bugs there, I'm using neem oil to scare them off since I saw the bites 2 weeks ago. Nothing jumps from the soil when I water it.
I'll update in a week

What did you spray it with to get rid of the bugs? Looks like whatever you sprayed it with probably burnt the leaves!

I used neem guard and after that some general anti-insect spray. You're probably right I wont use that anymore.