Man, I see several problems, or rather symptoms here.
Starved for mobile nutrients. But that could be because your VPD is off stalling respiration. Or could be PH out to lunch - i.e. bad readings.
They look both too wet and too dry at the same time. Diagnosis is hard when you have multiple issues going on. Many look the same.
I see white PVC - is that air lines? And it looks like you have 3" connecting the totes, is there a supply as well or is this a giant Kratky setup?
When you shocked the system and it did not respond, what were you using?
What is your source water, was there already chlorine in there? What is the PPM out of the tap if using tap water?
If this were my setup, I would empty and refill with RO. Then I would use H2O2 and these strips:
to bring it to 5 - 10 PPM H2O2 just to make sure you got rid of the root rot. Give it 1 or 2 days, test again, and when it gets very low on the test strips do a partial water change and add in the benies. Now you have a known solid start point.
At the same time I would drop the RH or raise the temp.
I would re-check and double re-check that my PH measurements are correct and I did not have an instrumentation issue. You want 5.7 - 5.8 at this stage.
Since they are pretty starved, I'd add a fair amount of N and
Cal-mag. maybe 300-400 PPM total if using RO water. When you fix the VPD, the nutes will make it to the top of the plant. New growth should immediately look much better. The old yellow leaves are toast - get rid of them immediately if dried and crispy, after day 2 if they are still part of the vascular system that is functioning - they can still help buffer big changes if they have any life left, but they won't make it long, nor are they necessary once you get under control.
I don't know about air movement, but that one little fan on the wall, if that is it, is not nearly enough for this size room. At this point, you need a steady small breeze across the bottoms of the leaves to prevent micro climates and get those stomata to open up.
I think if you got all this dialed in, I would lower the lights to bring the temp up and encourage growth. Your internode is not bad, but could be tighter. I assume with the tiny net pots you are not trying to grow trees here. If you are trying for little bushes you probably want more light, but only after the other stuff is under control or you will just burn them up.
PS: good job on asking the question with proper pics and data. Makes it so much easier on the people helping.
