Man I’m sorry to hear about your troubles.
My first thought was copper in the display but I see you didn’t use copper in display.
but I’m still thinking some kind of contamination possibly? It may be worth a ICP test just to know for sure. (Maybe a rusty component somewhere causing contamination?) or maybe air fresheners or something else being used near the tank?
second thought is maybe lighting is too intense? Maybe during the switch something was changed?
I don’t think this is your issue but a little po3 and no4 is good for the corals. Your levels are at zero. Maybe let them increase a bit. My po3 is .5 and no4 is 20-25 and things seem to thrive (I know many will say those levels are high, but this has worked for me. Tank has run these numbers for over a year)
but if it was me, the first thing I would do is an icp test. It’s well worth the $30 to know for sure if it’s copper or other elevated levels. Second I would search for rusting screws, pump parts, expanded magnets etc. The next thing I would check is for stray voltage.
good luck my friend, I hope you get to the bottom Of this issue. Take care and happy reefing.