Caulerpas tend to be aggressive growers and send anchoring "shoots" into nooks and crannies in the rockwork from which new "leaves" or " frond" emerge and on and on it goes. They are very difficult to remove if ever you should want to, so be very careful about allowing caulerpa species to grow in your reef. Removal, once it's established, of all of the anchored shoots is daunting and even if you think you've gotten it all, you haven't, and it starts to grow again with it's stongest growth coming from remote parts of the rockwork where it becomes even more entrenched. At that point, only a taking down of the rockwork in your reef would enable you to solve that problem.
Some people resort to Tangs and Foxfaces to keep Caulerpa in check, but if you search the forums here in RC for postings on that, you'd see that this isn't always a solution. Not every fish of that kind will eat it. I had a problem with Caulerpa at one time and a Striatus Tang ignored it.
Another problem with caulerpas growing in your reef is the way that they can "go sexual" which is another method of reproduction. Essentially, they release some kind of reproductive mix into the water column that would effect the quality of your reef's water and this can cause significant damage to your system. There are ways of attempting to control that, which, I believe, involves regular trimming....Maybe someone will chime in with more precise info on this caulerpa related issue.