Please help with my 12/12 from germ!

Hi all got a few questions about my 12/12 from germ.As you can see from the (not so great) pics, my plants are spikeing up on the sides of leafs and drooping. I give them nutes every other water. I water when soil is dry around 2 inch below surface.
There in canna coco and i use canna bio veg. And i have not used boost or floures yet due to only started seeing hairs the past week.But have been told that the soil i use has a stable ph so i dont need to check it by my local hydro store. i do believe this due to when i do soil (rarely more of a hydro guy) they 9 times out of 10 tern out nice. Also the leafs feel dry/crispy lower down. New growth looks ok but starting to spike up on sides. One plant looks fine just drooping a tad. Its more the one i topped and the other plant you see in pics.
just very strange as my 3 blue cheese scrog is growing fine with no issues (hydro).

INFO
600 HPS
5 inch cooltube with cabon filter and inline fan.
been growing for about 6 weeks.
Royal queen fruit spirit
Temps day 74-78f
Temps night 60-65f
10L airpots
Canna coco soil

If theres anything i have missed out please let me no.
Hopefully someone can help.
Please no bullsh*t just honest experience help.
Thanks in advance. ...

Most likely weak heat stress. Keep going.

Iv never heard of weak heat stress what's that bud?

Do you mean like not that bad heat stress ?

Come on people help me out....

Are you taking pics during lights off? That's a no no.
How close is your light?
If I were you, I wouldn't trust whoever told you 'your soil has stable PH'.
It very well might, but the grower can easily change soil PH if they're putting in water with nutes and PH of 4.5, or tap coming out at 7.9 (like mine does).

Naa lights were on mate just take them out as my phone don't like the hps light.
Yee that's very true mate. Il start taking note of the ph.
I have had a monster plant(pic of my avatar) was in soil and never looked at my ph who whole grow and was fine. I did think that it could be root bound as roots were poking out bottom so I put in 20l tubs today. My light is about 1 and half foot away from canopy and by hydro ones are fine with how far it is but since reading your post I moved a lil further away. And see how it goes. Thanks for the advice bro. So many people look but don't comment lol

All good now after putting in 20L airpots and giving them a nice hit of a+b nd boost and 3-4 days later started growing nice new growth. Prob put it down to root bound and nute def. thanks all for your help much appreciated!