I had a tank full of fish (mbunas and barbs) with my clown loaches and one of them came down with ich when I put some crushed coral in the filter to raise the ph for the mbunas. Well it raised it instantly like up a whole point (to ph 8.0). One of the clown loaches came down with ich BAD. I know you live and you learn it was stupid.
Anyway.....I dosed them with the amount of salt someone recommended to me and upped the temp to I think it was 80-82 degrees, for 3-6 weeks I think it was. I didn't add all the salt at one time...just a nice dose everyday...took me a week to get the right dose in there....I had already learned my lesson about changing things too fast.
It cured the ich and everyone was fine....just make sure you do a water change immediately after treatment is over.