Anything to do with testing your pool water, including pH, total alkalinity, calcium hardness, and more.
Everything to do with keeping your water properly balanced, especially in terms of pH, alkalinity, and calcium hardness.
All things to do with sanitizing, disinfecting, or oxidizing your water. This includes chlorine, bromine, and many other alternatives.
Calcium Hypochlorite: Should You Use This Type of Chlorine in Your Pool?
Any pool chemicals that apply outside of regular water balancing such as stabilizers, flocculants, algaecides, and more.