I had a similar experience as 'CanadaWest'. My tank was sooooo overrun with aptasia that you literally couldn't see rock. I'm sure there were thousands. I tried peppermint shrimp, with no luck.....they probably couldn't keep up.
I finally got a CBB, and the first 2 died
, but the third one I got did great, and now I can't find a single aptasia in my tank anywhere (except the sump), and he's doing great!
I don't know why the first 2 died, but I know the LFS was having a hard time keeping them alive at the time too.