I would leave the main tank empty of fish for at least a month to get rid of the ich. You need to move the fish to a QT for whatever method of treatment you decide on since inverts cannot tolerate some methods such as hyposalinity or using a copper based product. Kick-Ick, I have used it but so I don't believe that it did the job as well as it is advertised.
I have read on some other posts and sites that ich has a one month live cycle and requires a fish in order to live. Correct me if I'm wrong on that one though. I asked the same questions about ich and inverts and decided the best way to go was leave the tank empty for at least six weeks of any fish and make good use of my quarantine tank for any new fish.
There's some great posts on hyposalinity and how to do it here, probably your best place to start treating.