Tony, the temp. does not kill ich at all, what it does is speed up the life cycle of the organism. If I remember right the cycle takes 2-3 weeks at 72 F. but only 5-8 days at 82 degrees. There are some individuals that develope a bit slower at any temp so you want to go a couple days past the normal cycle. I just set it at 84-85 degrees, this is high enough that ten days of salt catches them all but low enough that it does not unduly stress the fish. You could salt treat a tank of sterlets at 62 degrees but you would need to do so for at least a month, possibly more. There is a chart for this on a research site somewhere but it has been a long time since I have seen it.