Need help with Marine Ick :(

[edikpok]

So I've had marine ich in my reef tank for a while now but it was fairly well controlled and I did not have any outbreaks of it until 2 weeks ago. I kept maintaining the water quality quite religiously and I am not sure what caused the outbreak. The fish that was affected most - the 6 line wrasse - died. My female clown shows some ich on her, while the male and cardinal don't show any ick.

I was thinking to setup a quarantine tank for the fish and treat them there. How does this work? will the ick in the main tank die if there is no host? how long should I keep the fish treated, away from the main tank?