I've heard that caulerpa sends runners/root into the rock, making it very difficult to completely remove. On that note, my Naso tang loves the stuff, so I've never had a problem with it getting a foothold in my display. And when I had to remove a coral beauty from the 156 gallon display, I just started feeding the whole tank mysis cubes out of a large net. After one week of training them to eat in the net, I not only caught the angel, but the naso as well!