Clownfish playing in flower pots and Brain

[Bigshow]

I have a little problem I have to flower pot corals and a brain that my 3 clowns like to play in. The two orange host in the brain but often play in. The black clown is a loaner. I recently put in a BTA a week ago and none of the clowns are hosting or even acknowleding the fact that it even exists. Any suggestions on what to do. Because eventually the clowns might kill the flower pots because they wont allow them to come out sometimes.