Very good site, I ought to be able to figure it out with this site. Seems like the way to go would be to have your return section in the middle with your refugeum on one side and your skimmer on the other side. As I don't have a Calcium Reactor, so I don't know the answer to this question. Can they be mounted in your sumps return section, just in case of a leak, the leak would be in your sump or, why bother because they never leak and just mount it out side of your sump.