Yes, definately treat in a q-tank using either copper or hyposalinity treatment, depending on what types of fish you have. There isn't any good, reef-safe ich treatment. Feeding the fish food dosed with garlic may help by boosting the fishes immune system.
BTW - Ich runs in cycles of around one week in length, depending on the water temp. Only during part of its cycle is the white spots visible. During treatment, just because the white spots are gone does not mean the the fish is cured and the spots may show up again if you stop treatment too quickly. Make sure you follow the directions for the treatment method you use completely and don't cut it short.
Here's the best website that I know of that describes marine ich and its recommended treatments of either copper or hyposalinity
ATJ's Marine Aquarium Site - Reference - Marine "Ich"