Purple Queen photoperiodic. DWC,LED

In week 3 the growth whilst in the oxypot v6 continued to be ok but when I topped it up with nutrients issues started. Brown spots between the leaves, dying leaves and "squished" growth of the stalks. Obviously what I should have done and will do in the future with the veg6 pot is give them a fresh nutrient solution when I transfer all the plants to their own pots. This was a bit of an experiment to see how long I could grow plants for in the oxypot veg 6 before needing to move them into their own buckets (the answer appears to be between 2 and 2.5 weeks). Day 1 pictures a number of issues can be seen I am hoping that after a few days in their fresh nutrient solution they are alright. Having serious difficulty with humidity and night temperatures at the moment - Im running two humidifiers but the humidity struggles to get over 50% and I don't understand why. I have tried adjusting the extraction fan to be higher or lower but it does not seem to make much difference. Keeping the room temperature at night above 18 and below 22 is difficult. I'm adjusting the house thermostat and radiator valve constantly to try find the sweet spot. TECHNIQUES Topped above the 5th node and trimmed lower, dead /dying leaves.