Ask a pool owner to name some of the worst nightmares they could imagine about maintenance, and chances are you’d get things ranging from persistent green water through calcium scaling to that mystery of chemical imbalances that would not go away. On the other hand, one term constantly surfing whenever one hits the research and information superhighway about pool chemistry is: Chlorine Lock. Although different people will refer to it differently, chlorine lock is a condition where your pool water refuses to hold free chlorine, no matter how much sanitizer you put in.
