I had pretty good luck with a combination approach. I had probably a dozen or so aiptasia of various sizes on about 200 lbs of liverock. I added about 5 peppermints, and they cleaned up most of the smaller aiptasia (along with a small
xenia frag I had in there), but they didn't seem to go after the larger ones. Those I blasted with some
kalk paste, and that took care of them. That was about 6-8 months ago, and I've never seen another aiptasia since.
I've reduced the number of peppermints in there, so I now only have 2 left. But I'd like to keep them in case there are any remaining aiptasia that try to make a come back. HTH