You realize they're gonna catch it again when you put them back in the DT right? Unless you get all of the fish out for the recommended time period (which is something like 92 days). Was it so bad that they couldn't shake it? Are you running a UV? What other measures are you taking to keep it under control in your DT? Any cleaner shrimp? Did they get stressed and that caused the outbreak? How do you plan to keep them from getting reinfected?
A 10g tank is pretty small for a 4-5" fish. You will have ammonia issues every other day, which means a lot of water changes and adding more copper, which is easy to accidentally overdose. You also shouldn't use copper with ammonia reducer because that can kill your fish. A live rock will help, but won't keep it down for long. I'm not sure if the copper will kill the beneficial bacteria on the rock or not but if it does, that will also cause an ammonia spike. Not to mention copper absorbs into rock, which makes it impossible to keep the copper concentration at the proper level. Also, once you put rock in a copper tank, it can never go back into a reef tank again. Personally, I wouldn't use the live rock and find another way. Maybe a 40g breeder? That will give you more water and time between water changes.
