Coral sand/chips = Calcium in water?

[zyblack]

I am curious to find out if by using coral chips/sand in your tank, do you get calcium in the water column? I mean do they actually dissolve to the calcium ions and carbon ions? I have heard of a few people using coral chips in their filter to buffer the water and also to dissolve calcium into the water column but does this actually work?

How do we tell how much calcium is in the water? Test kit again?

[barmby]

In a way, coral chips do buffer the water parameters such as preventing it from been too acidic. Very frequently used in koi and aro keeping