I've been keeping RBTAs for ten years and they almost never have bubble tips, until recently. I replaced my 250W MHs with AI Vegas and one of my RBTAs is right under one and it has consistent bubble tips. It still seems healthy. If it was stressed, I think it would wander away or go deeper. The other three clones I have, which are farther away, don't do it, except one that occasionally peeps out from behind a rock and gets bubble tips in the light. Just thought it was interesting.

Jack