Calcium supplement

Does anyone add calcium to their tanks?  I think my tank might have a
calcium deficiency, since the local water is very soft, and my amazon
sword is putting out leaves that are somewhat stunted and mishshapen,
but otherwise normal.  I want to add a little calcium, but really don't
want to increase the KH using carbonate.  I have thought about
adding some calcium chloride that I have, or maybe some eggshells.  Does
anyone know what calcium chloride would do, or what form the calcium is in

 Thanks in advance,
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