Yes using a hospital tank would be the best way to treat the fish. From my experience medications do not work well, the best treatment for ich IMO is hyposalinity, lowering the salinity to a level witch the ich cannot live. This is done in a hospital tank with no LR, LS anything except for fish because other live things can't handle low salinity. Fish can live with ich for at least 2-3 weeks, depending on how long the fish has already had the ich for.
Hyposalinity may take a little while but it is effective if done right. You should move all your fish from your main tank(hopefully you don't have too many), even though only one fish may have visible signs of ich that doesn't mean the other fish don't have it as well, once one fish has it then its too late, it has allready infected your tank and ich cannot live without a host fish so if you take out all the fish the ich will die off. After you move the fish into the hos. tank you slowly lower the salinity level over a week doing water changes using freshwater (no salt) until the level is at 1.009. While the fish are in the tank you need to check the water parameters often because the low salt level can mess up you Ph so its good to keep an eye on that. You leave the fish in the low salt level for about 3 weeks, don't worry about anything in the main tank, inverts, coral, ect. ich only effects fish. Once there are no visible signs of ich after a long time then you slowly raise the salinity the same as how you lowered it. While the fish are in the hos tank it is good to feed them garlic soaked foods, this helps them get rid of the ich. Once the salt level is normal again you should leave the fish the hos tank for at least 2 weeks to make sure the ich is gone and that your main tank is rid of it.
Hope this helped you.
