IMHO
Fantastic advice about flushing etc, was already given. Just to use nutrients too. Your roots aren't that bad. Infected, yes. But not out of control.
If it was me.
If you already have lots of oxy. I know it's a pain in the arse. But I'd be flushing, and changing the reservoir a couple times a day, until it clears.
It shouldn't take long. Maybe a week, tops.
A little h2o2 wouldn't hurt either.