Part of the reason it came to me is to justify a laser. The other part is because I saw some little tentacles peeking up out of the sand that look a lot like apts.
And you don't have to spend that much on a laser. Some (china sales) sites have them for under $50. If it worked well enough, it might even be the next wonder product for aquaria. Probably would want to design a waterproof version... Maybe $150 for an selective, target-able aptasia and majano killer? I'd think you'd sell plenty of that.
I'd think you might also be able to selectively go after a number of other difficult to remove critters with it, possibly including algae.