You notice that there are deposits of calcium carbonate (a hard, white substance) along the inside of the walls of the kiddie pool. what types of reaction caused this?

Calcium can build up in your pool water when the pH levels are off and leave deposits on your pool tiles. It's similar to what happens in your bathroom sink, toilet or bathtub.

More details:

There are two types of calcium compoundsthat form in pool water and create scaling--calcium carbonate and calcium silicate. Both are caused by a pH imbalance. Your pool should be at a pH between 7.4 and 7.6.

I hope this helps.

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).