You will have to leave your fish in QT for weeks, long enough for the W/S to die out in your tank, I know a few people who have tried this and none have been successful, but I guess it can be done. IMO you are better to leave the fish in the tank and address the stress that is causing them to get it. A lot/most tanks have W/S in them, healthy, happy, unstressed fish don't normally get it. Stress the fish by puttting them in a small tank, catching, etc etc will just cause increase the chances of losing them.
Just my option.