Roger,
Do you have it all connected together into the same sump/filtration or do you have them separated?
The reason I ask is because I have a 29gl BioCube that I was thinking of making into a frag tank, pretty much for the same reason you have yours and to make some frags for friends and family.
The issue is that I can't decide how to go about it? I don't want to get a whole new sump/filter and skimmer to clean and maintain, but I don't know which way is the best to hook everything together.
I think my sump and skimmer can handle the load of both tanks, but I'm not 100% sure.
I wanted to get some feedback from you as to how your setup works today.