DO NOT PUT COPPER IN A REEF TANK. That is a bad idea. There are other, less risky methods of ridding your tank of aptasia.
I have found peppermint shrimp work, but may take a long time, depending on other things in the tank that they can eat.
The concentrated kalk works very well. You may have to try it 2 or 3 times though.
The copperband butterfly seems like a great idea, but I have no experience with it.
Good luck!