Here's the best Ich article on the net written by Daveedka-
http://www.aquariumboard.com/forums/articles/25.htm
The problem with salt is that it causes osmotic shock when added and removed too quickly.
If you started adding salt already it is best not to remove it. Weakened fish do not deal well with osmolarity changes.
I usually don't recommend using salt because most people panic and do massive water changes when fish have ich. Doing large scale water changes after the salt is added is a huge mistake that will probably kill the fish.
The dosage in the Daveedka's article works fine with clown loaches, if it is administered properly. It needs to be added slowly; over the coarse of a few days. After the last ich spot is gone, give the fish 2 more weeks of treatment. This will give the fish time to recover. The salt should be removed very slowly through small water changes. I'd do no more than a 2 - 20% water changes per day.
*2 teaspoons of salt per gallon of water is the proper dosage. If you try much less, the concentration of salt might not be strong enough to kill the ich parasites.