You know by having two separate stacks, you can do the egg crate in between if you want to add in fish at different intervals like that guy was talking about at the swap. It was an interesting idea, BUT I do have to say some fish will never get along no matter how you keep them apart. My Dory I got killed my anthias after they all been in there over a couple of weeks. My sixline wrasse I got from James killed my Target Mandarin after it's been in there for two months. So I don't completely agree with him. I got a Yellow Tang from Kathy that keeps my Regal in check, but Dory is shy to come out now.... Only comes out to eat, that's about it....