Ich can only beat down stressed fish. Fish naturally have a slime coat to fight off ich for the most part. There are many people who live with ich and do just fine. This can only be done with perfect water conditions(rodi and no nitrates) and a stress free environment(no fish aggression).
For example, when I was running a (fish only/tapwater) tank my blue hippo tang loved letting me know when the nitrates got too high he would start showing a small amount of ich. I would do a series of water changes to knock the nitrates down and he would go back to being fine.
Before you go the QT route consider all the possibilities of reintroducing ich back into your main tank later down the road on accident and decide if it's right for you.
Also consider a uv sterilizer to reduce the amount ichs swimming around looking for a host. This part is highly debatable and is unproven but I still use it as a just in case it works kinda thing.
I realize this post is late but maybe it will still help you in the future or someone else.
Hope everything worked out.
Jerry