It sometimes takes a few weeks to treat and get rid of ich, it has a 4 stage life cycle, and only vulnerable to the treatment in 2 of those cycles (and at any one time, all 4 stages are present). If you use salt, you need to have a concentration of at least 3ppt (Parts per thousand) the water in the tank will actually taste salty, if you can't taste saltiness, ich are simply irritated not killed. Turning up the heat only speeds up their life cycle so the vulnerable stages occur faster.