Im sure others will chime in, but buying a creature to eliminate something like aptasia is only going to cause you more problems in the future.
Once the aptasia is gone (if they even eat it?) it will starve....i dont have any personal experience, but have read that they die easily this way, and that they foul up the tank something feirce.
Did you try joes juice or the kalk paste or even lemon juice to rid them?
What worked for me was a syringe (my wife is a pharmacist so i got a nice one! lol) and I hooked up some airline tubng, and squirted lemon juice right at them as close as I could get before it got scared and closed up.
Of course, I cant get all of them, but doing this every couple of months is no big deal to keep population under control. I dont think they are that bad a thing in the tank as long as you control the population. I have seen ine collect crap floating in the water, so to me, they provide some extra cleaning.