Unresolved Some form of nasty growing

You may also want to stop dosing trace elements if doing so. If I had to guess, I would say a mix of dinos and cyano. They seem to go together. Maybe even a bit of bacteria or fungus mixed in for good measure... If you have access to a microscope, you can get a better idea though.

Also, vacuum the heck out of any detritus. And does it come off easily? Cyano tends to, dinos not as easily.