calcium reactor questions

[rickwaines]

It would seem to me a great piece of gear to have in ones sump. I am planning a tank that will have a footprint of 24 inches, and therefore, a sump that has a footprint of 24 inches. I am already planning on a skimmer of course. Are there excellent quality calcium reactors that are designed for small spaces?
I am not planning for hard corals at this point if that makes a difference.

and as usuall, thank you in advance, rick