Need the heat for it to really be effective. It messes with there life cycle by speeding it up to much. If you can get your hands on a heater any time soon a little garlic added to their food (and in extreme cases to the water) is supposed to help kill ich. You can sometimes find liquid garlic in health food stores. I have not personally used the garlic method because the heat is so effective, but I have heard good things about it. It also enhances appetite. Oh, and that is a lot of salt for the cories.