I used a couple of very small brass fittings on some plumbing years ago when I was first starting. Brass is a copper alloy. Copper is poison to most aquatic organisms. I did find a good way to eradicate GSP though, LOL!
This just struck me.
Could a copper based medication be used to eradicate aptasia? Of course depending on the infestation if it kills it off managing water quality would be important, and any inverts would need to be removed. Hmmm?