Hmm, I would put your julidochromis in the 19" tank and get him some buddies, they do much better in groups. Will be happier, plus a group of them is interesting to watch. When you put social cichlids alone, they get kind of boring, just sit there. When in groups, you can really see their natural behavior. And that 10 gallon is going to get pretty cramped for the juli after a while. You could get some of the shelldwellers as well in the 29 with the julies, have a tanganyikan theme tank.