Be aware of oodinium/marine velvet too, since you're talking about really fine, white dots. It looks more like a frosted sugar coating. I have never seen anyone at this site since I've been here talk about this stuff, but it worked for me with a velvet outbreak. It's called Revive.
I did 2 treatments w/in 1 week. Maybe got lucky, but saved 4 fish, and all my coral after treating in the main tank. 1 2 weeks later, I was adding fish. 6 months later, no problems.