Can you put it in a lower flow area for a bit? It's really hard to say, your parameters seem fine and you mentioned a clean icp test.
Elegance are hard to keep and apparently the polyp bailout might be some sort of bacterial infection with a poor prognosis. I have no personal experience though.
I built an egg crate box and put it around it to protect the tank of it totally bails. (Which I think it will) it’s crazy, still huge fluffy and happy right now. Looks like only holding on by a thread though