It was prob not the bayer. Bayer works great and never had an issue with it. As long as you rinse well. I just bought one myself and brought it from Virginia to North Pole Alaska and did the same thing but recovered well. There is still hope my friend!
Update...I moved it to a new spot with lower lighting and have been playing around with the power heads to lower the flow it gets. Then I had to take a last minute trip out of town for a week. I wasn't sure what I'd find when I got back but it's looking really good. In the second picture you can see the back half is definitely dead. I'm hoping the living part will grow and repopulate it. I'm target feeding it once or twice a week with aqua vitro fuel per my lfs suggestion.
I had some goni do the same thing but they came back and look great now, it was after a dip too. Also, mine live being BLASTED by a power head. I have them right in front of my rw4 on wave mode and they're really happy.