[Flanders]

I finally got rid of it by essentially starving the tank, using tons of GFO, dimming the lights, diligent manual removal every few days and a bunch of emerald crabs - they will eat it, slowly. You're already way ahead of me if your tank is big enough for a foxface and zebrasoma.

Relentless, yeah, that's the right word. I'd probably call the scrubber a failure, pull it offline, sterilize and start it over again after you get it out of the display tank which I can assure you is possible. Water changes won't do anything. Maybe grow some chaeto to get you over this hurdle.