Good move. QT is the only way... From experience, Melafix doesn't work. Rid-Ich does work. It has fisheries grade formaldehyde and zinc-free chloride salt of malachite green. I've used it successfully in my QT to fully treat ichy newbies before adding them to my main. It's safer than copper, and easier on fish than straight malachite. Not safe for inverts though... I'm never using anything else...
Btw, never add anything to your main!