good luck. i'm currently in a similar boat as you are...i have been keeping the ich at bay the natural way, feeding my fish, keeping them healthy and they have been fighting the ich...well the only one to have it was the blue tang anyways and it seems all gone now...with the help of cleaners and a very healthy diet they can have a strong immune system and over power the ich...my theory is that once the fish are too strong for the ich to host onto them, then they will die from the lack of a nutritional source (aka host)