I'm invested in hydro at this point I'm not trying to spend too much more lol. But yeah my ph hasnt really bounced up or down nothing too crazy the whole grow. I usually keep it inbetween the 5.5-6.5 range. Water temps when it gets hot is usually 75-80. Air temp when it gets its hottest is like 85 but for the past 2 weeks I've been monitoring and taking care of the both HEAVY. So air temp usually sits around 77 and water temp at like 68-70. RH isn't really much of an issue anymore I've got a good humidifier that keeps it in that 60-75 rangeTotally your call. These plants are resilient AF but I would personally be concerned with the exposure to the paint chemicals.
If you got nothing to lose and time to kill, switch buckets, only using fresh water and no nutes for at least a few days to try and get any shit out of the plants.
Hydroguard is a great suggestion and will help with root rot. "Help" not a complete solution.
What are your water temps normally? What do they spike to where you need to use frozen water bottles?
I also 2nd that PH swings is an issue. Test PH at least twice a day for few days to see if PH is swinging and how much if it is.
Or switch to coco lol.