I thought I'd split this inquiry off from the post linked below so as not to sidetrack that threads focus.
I've been a member for a while and seen dozens and dozens of posts about high calcium levels and scaling and the responses have always been that the only ways to reduce calcium hardness were to drain and re-fill with less hard water or call in an expensive, not commonly available service to perform RO filtering.
In the post above, it mentions a method of eliminating calcium using sequestrants and filtering out the calcium. Is this real? Why isn't this method talked about more often? Is there a downside?