TL;DR
Free chlorine is the portion of chlorine in pool water still available to sanitize — hypochlorous acid and hypochlorite ion that have not yet reacted with contaminants — as distinct from combined chlorine already bound up as chloramines. Pools target 1 to 3 ppm free, with effectiveness rising as pH drops toward 7.4 and falling sharply above 7.8.
What it means
Free chlorine is the portion of chlorine in pool water still available to sanitize — hypochlorous acid and hypochlorite ion that have not yet reacted with contaminants — as distinct from combined chlorine already bound up as chloramines. Pools target 1 to 3 ppm free, with effectiveness rising as pH drops toward 7.4 and falling sharply above 7.8. A pool that smells strongly of chlorine usually has too little free and too much combined chlorine, the condition shock treatment exists to fix.
Where it sits in the glossary
Free chlorine is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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