{"id":13637,"date":"2026-11-06T02:48:16","date_gmt":"2026-11-06T02:48:16","guid":{"rendered":"https:\/\/aiper.com\/blogs\/?page_id=13637"},"modified":"2026-11-12T04:43:38","modified_gmt":"2026-11-12T04:43:38","slug":"free-chlorine","status":"publish","type":"page","link":"https:\/\/aiper.com\/blogs\/glossary\/free-chlorine\/","title":{"rendered":"What Is Free Chlorine?"},"content":{"rendered":"  <div class=\"aiper-glossary\" lang=\"en-US\" data-result-one=\"{count} term\" data-result-many=\"{count} terms\" data-empty=\"No terms found. Try another name or clear the filters.\">\r\n     <header><p>Pool Water Chemistry<\/p><h1>What Is Free Chlorine?<\/h1><p>Free chlorine is the chlorine residual measured as available for disinfection rather than combined chlorine.<\/p><\/header>\r\n   <figure><picture><source media=\"(max-width:600px)\" width=\"600\" height=\"650\" srcset=\"https:\/\/aiper.com\/blogs\/wp-content\/plugins\/aiper-core\/glossary\/free-chlorine.svg?ver=0.5.11\"><img src=\"https:\/\/aiper.com\/blogs\/wp-content\/plugins\/aiper-core\/glossary\/free-chlorine.svg?ver=0.5.11\" alt=\"Illustrative proportional bars: free chlorine 3 ppm, combined chlorine 1 ppm, total chlorine 4 ppm. Total minus free equals combined. Not target levels.\" width=\"600\" height=\"650\" fetchpriority=\"high\" decoding=\"async\"><\/picture><figcaption>Illustrative proportional bars: free chlorine 3 ppm, combined chlorine 1 ppm, total chlorine 4 ppm. Total minus free equals combined. Not target levels.<\/figcaption><\/figure>\r\n   <section><h2>Understanding the Concept<\/h2><p>A chlorine test distinguishes free chlorine from total chlorine. Their difference is the calculated combined chlorine result.<\/p><\/section><section><h2>Common Misunderstanding<\/h2><p>Cyanuric acid changes chlorine chemistry and activity. A free chlorine reading alone does not establish that water is safe.<\/p><\/section>   <section><h2>Related terms<\/h2><ul><li><a data-glossary-link=\"related-term\" href=\"https:\/\/aiper.com\/blogs\/glossary\/chloramines\/\">Chloramines<\/a><\/li><li><a data-glossary-link=\"related-term\" href=\"https:\/\/aiper.com\/blogs\/glossary\/combined-chlorine\/\">Combined Chlorine<\/a><\/li><li><a data-glossary-link=\"related-term\" href=\"https:\/\/aiper.com\/blogs\/glossary\/cyanuric-acid\/\">Cyanuric Acid<\/a><\/li><li><a data-glossary-link=\"related-term\" href=\"https:\/\/aiper.com\/blogs\/glossary\/saltwater-chlorination\/\">Saltwater Chlorination<\/a><\/li><li><a data-glossary-link=\"related-term\" href=\"https:\/\/aiper.com\/blogs\/glossary\/total-chlorine\/\">Total Chlorine<\/a><\/li><\/ul><\/section>   <section><h2>Learn more<\/h2><ul><li><a data-glossary-link=\"tool\" href=\"https:\/\/aiper.com\/blogs\/pool-chlorine-calculator\/\">Pool Chlorine Calculator<\/a><\/li><li><a data-glossary-link=\"checklist\" href=\"https:\/\/aiper.com\/blogs\/checklists\/weekly-pool-maintenance-checklist\/\">Weekly Pool Maintenance Checklist<\/a><\/li><\/ul><\/section>  <\/div>\r\n  <script type=\"application\/ld+json\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@type\":\"DefinedTerm\",\"name\":\"Free Chlorine\",\"inLanguage\":\"en-US\",\"description\":\"Free chlorine is the chlorine residual measured as available for disinfection rather than combined chlorine.\",\"url\":\"https:\\\/\\\/aiper.com\\\/blogs\\\/glossary\\\/free-chlorine\\\/\",\"inDefinedTermSet\":\"https:\\\/\\\/aiper.com\\\/blogs\\\/glossary\\\/#terms\"}<\/script>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":3,"featured_media":0,"parent":13585,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"aiper_reading_time":1,"aiper_last_reviewed":"","aiper_reviewer":0,"aiper_related_ids":[],"aiper_layout":"tool","footnotes":""},"class_list":["post-13637","page","type-page","status-publish","hentry"],"lang":"en","translations":{"en":13637,"de":13756,"fr":13807,"es":13857},"_links":{"self":[{"href":"https:\/\/aiper.com\/blogs\/wp-json\/wp\/v2\/pages\/13637","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aiper.com\/blogs\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/aiper.com\/blogs\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/aiper.com\/blogs\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/aiper.com\/blogs\/wp-json\/wp\/v2\/comments?post=13637"}],"version-history":[{"count":1,"href":"https:\/\/aiper.com\/blogs\/wp-json\/wp\/v2\/pages\/13637\/revisions"}],"predecessor-version":[{"id":13649,"href":"https:\/\/aiper.com\/blogs\/wp-json\/wp\/v2\/pages\/13637\/revisions\/13649"}],"up":[{"embeddable":true,"href":"https:\/\/aiper.com\/blogs\/wp-json\/wp\/v2\/pages\/13585"}],"wp:attachment":[{"href":"https:\/\/aiper.com\/blogs\/wp-json\/wp\/v2\/media?parent=13637"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}