Stressed fish will get ick. How else do they tell you something is wrong....
I just threw an icked fish in more suitable accomodations in another tank. NO more ick. (the trigger and grouper seemed to be causing some stress to the heniochus)
Pay attention to what is CAUSING the ick. Then the shrimp/garlic/etc come into play. I can certainly understand how it can be a problem if you are new to the hobby.
Understand what is stressing your fish. It can be as simple as a temp problem, or a flow problem, or an aggressive tankmate, or obviously water quality issues....alkalinity is a big stressor for fish...I found that out years ago with that coral-vital apple juice.
In the interim, my treatment of choice would be hyposalinity.
