The best source of calcium is SCD home made yogurt, Coral Calc is also (supposed to be) negative charged.
Else just run some current through it like that page.
YOu can do the same to VitC as well.
Look at the carbon part of that page, both VitC and Calcium can be suspended by mixing with water and charged this way.
But don't take my word, charge one load of your VitC and you will be able to tell the diff immediately..