Because you were led astray, CBB are really not an aiptasia eater. They eat anemones yes but purchasing one to solve an aiptasia problem often does not work. CBB is a fish best left to those devoted to feeding them specialized foods such as clams, most CBB perish from starvation.
Yes you can keep them successfully but a hobbyist needs to understand that this fish can be difficult to feed, may not feed with more aggressive fish types present.
A much better choice is true Peppermint Shrimp, and eradication of aiptasia prior to introduction to the display.
Many keep this fish successfully, but as previously stated the majority perish.