WHAT is the problem ?

So i got this weird yellowing on leafs , looks like burned . Its not getting hot on me hand , when i put it on top of the plant.
Ph is fine always been spot on.
Got one fan moving air around , then got carbon filter on ever 2h .
400w
7 plants
Canna soil
5 weeks and 2 day flower
Temps always jumping between 19 c -30 c
Nights always colder.
Humidty jumps also around 30-50%
Depends when lights on and carbon.

Otherwise they healthy girls.
The one got yellow on leafs for some reason top bud is just like stunt . Boytom grows but top just little hair and no change ?

Anyone knows what could of caused it ?

My novice guess is the plant is getting too much I'm the way of nutrients. Looks like they're burning a bit. Back off a bit and see if it gets better.

Someone more.experienced than I am will chime in soon...

Ye well could be , i had old nutes had some salt building on bottom of nutes.... just got new ones . But i just cant figure out why top bud just dont grow , stunt for weeks .... 10 times smaller than others.

I'm honestly not quite experienced enough yet too comment on that, but ill be interested to find out what happens. That seems weird for just one to come to a halt without signs to the others.

I hope not genetic thing or second fim didnt harm the top.

I reference these sometimes when trying to figure out what the problem is, maybe could help with your identification of the problem.

That is great table ! Will be loads of help with that table and once loupe will arrive too ! I gonna try harvesy these with cloudy trichomes for uplifting high .

For stunted growth should i try give more k and ca ?

Stunted plant got leafs kinda truned upwards and really shiny .