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.
One of the most common methods to date volcanic rocks uses potassium (radioactive parent) and argon (stable daughter). Potassium is an element found in many minerals and rocks, and it normally has an atomic mass of 39.