Pretty much all coral, even soft coral use up calcium carbonate. While they may not form a skeleton like LPS and SPS, soft coral do create these small sand grain size bits of skeleton in their tissue called sclerites.
You're going to need to come up with some kind of system that works for you if you want to keep your levels optimal.
This article might help.
An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php