You can mix it, or just use it dry, like you would Kent Turbo Calcium. It's Calcium Chloride dihydrate (CaCl, with two H2O's). Kent Turbo Calcium is anhydrous Calcium Chloride, which is a bit more potent.
$59.99 isn't too bad for 50lbs, considering 1lb of Kent Turbo Calcium runs $10-$20.