Sources of Calcium

I live near Fresno, CA (Naval Air Station Lemoore, CA to be precise) and am having trouble finding inexpensive sources for raising my water's calcium level. I checked Lowes and Home Depot and have been making calls looking for calcium chloride. I get alot of blank stares, maybe because

I took a sample to the pool store and they weren't too concerned. It tested somewhere between 50-100 for them, comparable with my own 60-70 reading. The pool is a gunite, pebble tech style pool at about 23,000 gals.

What should I be looking for? The pool store sells CA at $10/#6 or $25/#15... looking for a cheaper option, not sure how much its going to take.

Calcium chloride is also sold as "de-icer" in products such as Peladow, Dowflake and Tetra often found in hardware stores. Of course, leaving in an area that may not freeze makes it less likely to find such products.

I found a source! The local pool store sells 15lbs for $25. I found a cement and landscaping shop in Fresno, just down the highway from me, that sold me a 50lb bag for $30. And he claims its between 94-97% Calcium chloride. I'm excited! Now I just have to figure out how much to add!

Use The Pool Calculator where in the CH section use "calcium chloride" not "calcium chloride dihydrate".