This is an interesting topic, not to take away from the original question but would a uv light or skimmer help to kill off some of the ich still swimming around in the tank over a period of time?
UV sterilizers does not kill full mature ich that is on the fish. A UV does however kill ich that is in the free swim stage so it is useful in diminishing the spread of the parasite. It should be noted that a UV also kills some beneficial life that is in the water as well so each aquarist must weigh the pros and cons.