The Difference Between Free and Total Chlorine
From Swim University
Most people when they are swimming in an inground pool are congnizant of one aspect of water chemistry: Chlorine Level. What people don't realize is that this seemingly simple measure is actually quite complicated. It takes an amateur chemist to understand water balance, and all of the various factors that can affect it in swimming pools. This post by Matt Giovanisci of Swim University, however, attempts to explain the components of chlorine within that complicated mixture.
Here is an excerpt from the post: