From 1 Stop Pool Pros
It's easy to assume that a swimming pool is "set it and forget it", but that really is not the case. Anyone familiar with swimming pool water chemistry understands that to achieve balanced, healthy water, one needs to understand the differing measurable components of the water saturation index. The important levels of pH, Alkalinity, Hardness, Temperature and Free Available Chlorine are all integral to achieving a safe, sanitary swimming pool environment. This post from 1 Stop Pool Pros gives a good primer on the different chemicals that are utilized to achieve balanced water in these important areas.
Here is an excerpt from the post: