I don't QT LR, and depending on the type of Coral yes I might QT.. Other I do a Lugols dip on and put right into the display. But there are several factors that go with that. Where I got it from, if it was on a central filtration unit.. etc etc etc. I also go over my corals with a fine tooth comb before ever putting them into my display as there are all kinds of other parasites that could be fine on one coral but not another.
Isn't it possible for ich to hitch hike in on LR, or anything, for that matter?