As pool season begins you’re probably stocking up on chemicals to keep your pool crystal clear. This is a great time to learn a little more about Chlorine and how it works.

Chlorine is far and away the most used sanitizing agent for municipal drinking water and swimming pools.  Most, if not all, municipal water supplies in North America use chlorine to sanitize our drinking water. Without the chlorine, the water would not be safe.


Chlorine is a reactive element.  It likes to attach itself to other elements or compounds.  It has a high electron affinity and also the fourth highest electronegativity.  Because of this, Chlorine is a strong oxidizing agent.  Since it is so reactive, Chlorine is usually present ionically bonded to another element.  It is most commonly found in nature as Sodium Chloride (NaCl), also known as table salt.

When you add chlorine to the water in your pool, a chemical reaction occurs.  The result is the creation of hypochlorous acid (HOCI).  Because of the acid’s neutral electrical charge, it can make contact with and breach the cell walls of microorganisms and bacteria, destroying them. In order for chlorine to do its job, the pH of the pool must stay within a certain range.  The CDC recommends a pH between 7.2 and 7.8 for the most effective chlorine use.

Pucks, Liquid, and Salt Chlorine

The majority of swimming pools are sanitized using a combination of ‘trichlor’ pucks and liquid chlorine.  Pools using salt-chlorine generation as their main method can still use trichlor pucks to maintain sanitizing while the pump is not running.  The Solar-Breeze NX solar robotic pool cleaner has a chlorine dispenser that holds two 3-inch trichlor tablets.  They travel around the pool all day and most of the night, resulting in more even and efficient sanitizing of the pool.

Got that Heavy Chlorine Smell?

A heavy “chlorine” smell around the pool is usually the result of chloramines.  Chloramines are created through the interaction of chlorine in your pool water with perspiration and urine from swimmers.  They not only smell bad, but irritate the eyes and throat.  Asthmatics have a hard time dealing with Chloramines.  This is a good reason to rinse off before diving in.
Home and pool chlorine products should be handled with care but not with fear. When you purchase liquid chlorine, transport it home in the trunk of your car or beside an open window.  Wear rubber gloves when you open the container and point your nose away as you pour it into the pool. Always store chlorine and other chemicals in a safe spot, out of reach of children.

Proper use of chlorine, along with regular removal of contaminants, will keep your pool in prime swimming condition all summer long.

Check out next How to Use Less Chlorine in Your Pool, saving you chemicals and money.