Unless there is some other problem in the tank, I would not only not go to great cleaning lengths(m aside from vacumming and water changes), but I would feed the bacteria to preserve the bio-filter and after a week of ich treatment your tank should be devoid of it, and then go right into a new fish. Ich is really pretty easy to eradicate, it is also easy to reintroduce so be wary of that as well. If there is no host (fish) it cannot survive contrary to popular legend.