a bta? I personally wouldn't frag mine. I would wait for it to split or just let it get big. I have watched some vids of people fragging theirs. You need to be careful to do clean cuts and to get it through the mouth. If you don't it will die
For some reason I think of my bta as a fish more than an invert, and it makes me cringe thinking of cutting it in half.
as for a bubble coral, see this thread
http://www.thereeftank.com/forums/f6...t=bubble+coral