A Pool Chlorine Glossary

“…unless water disinfectant levels are properly managed, a dip in the pool or spa can result in illness, such as diarrhea, swimmer’s ear or skin rashes, including athlete’s foot.  Used properly, chlorine pool and spa disinfectants help keep our recreational waters safe by destroying the waterborne pathogens that can ruin our pool and spa experiences.”

American Chemistry Council

girl in swimming poolChlorine must be present in your swimming pool at all times in the proper amounts.  Whether you use pool chlorine tablets, sticks, or granular chlorine, it reacts instantly with waste products to sanitize your pool water and make it safe for swimming.  To aid in your understanding of how chlorine acts as a sanitizer in your pool, here is a short glossary of pool chlorine terms:

  • Available Chlorine: A term used in rating chlorine products as to the strength of the chlorine available per equal units of measurement.  It is usually rated as percent.  For example, 90% available chlorine means that 1.0 pound of that chlorine compound has 0.9 pounds of pure chlorine strength.
  • Chlorine: A chemical element that exists as a gas in its elemental form or as part of a chemical compound which is an oxidant and biocidal agent used in disinfecting pool water.
  • Chlorine Demand: The chlorine needed to kill algae and bacteria in a pool.
  • Chlorine Residual: The amount of chlorine remaining after the chlorine demand has been met.
  • Combined Chlorine: The portion of the total chlorine existing in water in chemical combination with ammonia, nitrogen, and/or organic compounds; mostly comprised of chloramines.
  • Free Available Chlorine: Chlorine that has not combined with other things in the water like algae or bacteria.  This chlorine is what is still available for sanitizing and can also be considered the chlorine residual.
  • PPM: The abbreviation for Parts Per Million.  The unit of measurement used in chemical testing which indicates the parts by weight in relation to one million parts by weight of water.
  • Sanitizer: Any substance that kills germs and bacteria, providing a sanitary water environment.
  • Pool Shock Treatment: The practice of adding significant amounts of an oxidizing chemical (usually chlorine) to pool water to destroy ammonia and nitrogenous and organic contaminants in water.  Usually requires achieving 10-15 ppm of free available chlorine.
  • Superchlorination: This term is often misused within the pool supplies industry.  Sometimes this word is used interchangeably with the term “shock.”  Other times, this term is used to mean elevating the current free chlorine level by an additional 5.0 ppm.  Under this definition, the only way “superchlorination” would also “shock” is if the current free available chlorine level is at least 5-7 ppm.
  • Total Chlorine: The sum of both the free available and combined chlorines.

Posted: Wednesday, May 25th, 2011 @ 7:35 pm
Categories: Pool Chemicals.
Tags: , .
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