QT it first, then dip/medicate/return if you notice anything. For coral a
QT doesn't need to be anything more than a cheap 5g tank, small powerhead (not aimed directly at the coral!), a 6500+K compact flourescent light or whatever might be appropriate to slowly
acclimate it to your display tank lighting, and frequent partial water changes. It'll save you tons of hassles in the long run and since it will only run for a few weeks when you buy livestock it really isn't very expensive.
