[OCDP]

For a frag tank, I'd go BB for sure. But if it's tied in with the main system, I am not sure how much of a difference it will make. Either way, go BB for the frag tank... that's my opinion.

As far as cleaners.. I'd use some astrea and turbos, any kind of grazer will do I'd think.

As for fish... depends. What kind of frags are you growing out? Various? SPS? Etc... that will help determine the type of fish to keep. But, if this is a frag tank, I personally would keep it fishless. Just for nutrients sake.

I am no frag tank expert, I don't have one.. these are all just my opinions, and what I would do. Some other will chime in soon enough to help you out.

Good luck.