"IF it is in the tank, it is there to stay" was what I was referring to. If there is no fish to host, the parasite will die, if it is put into a display that once had it, and it was cleaned off the fish, and the display was left without fish for a period of time of 6 weeks or more where the ich had no host and died, than it is not there to stay. I was wrong about posting kick ich, I meant to comment on the no sick fish which also falls into the same category. The reason why you may see no spots after treatment is because of the life cycle of the parasite, not from it's removal.