They'll clean the fish a little, but they won't totally get rid of ich. The best way to get rid of ich is to move all fish to a Quarinteen tank, and do hyposalinity for a minimum of 4 weeks.
Feduke
Even though the ick is not on the fish it is still in your tank will keep attaching itself to your fish. SO you should do what the post's above said, I did my tank for 6 weeks and now there is no ick at all