The only way to kick ick is to remove all your fish and QT them for a period of 6-8 weeks. This will allow 2-3 cycles of the parasite to occur, without a host they cannot live, therefore removing it from your system.
I'm going through this process right now. My black tang that I got stressed out really easy and within two days was completely broke out in ick, then my powder brown started getting it. So I know have all my fish removed from the tank and resting peacefully at SITC! Thanks Marcye!!!
Hopefully in 6-7 more weeks I'll have fish in my system again!!!