I did a little checking into medical grade vs. commercial calcium supplements. Are you sure that 100% measurement is by volume, and not the recommended daily allowance? That is how most human supplements are measured. Pure calcium is highly volatile and has major chemical reactions with air and water. It is available by prescription only and usually in injectable form to be used intravenously in very tiny quantities. It must be premixed several hours prior to use to avoid unwanted chemical reactions from damaging blood and nerve cells.
Calcium gluconate is often dosed out at 100% RDA, which is 400 IUs per "serving" of 5 mls, but has a volume of 9% calcium. There is far more sugar than calcium in it. So a commercial reptile product contains a higher percentage of calcium by volume than the most commonly prescribed medical grade calcium.
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