What is Chlorine and how do I use it in my Swimming Pool?

Chlorine is the #1 sanitizing chemical in swimming pools.  Often referred to as Cl, it helps kill germs and viruses and keeps your pool water clean and safe for swimming.  Maintaining a proper amount of Cl in your swimming pool will help to eliminate algae and bacteria that can be harmful to a swimmer.  Many other pool chemicals can drop to a zero level and you might get away with it for a little while but not pool Cl.  If the level of Cl drops to zero for any extended period of time then you will have pool water problems. Cl must be added regularly and tested for accuracy to ensure chlorination is at the correct level.  Remember, adding too much is never good or safe for swimming and too little will not clean or disinfect your pool water.

What type do I use?

 Liquid chlorine is my choice for perfect sanitization.  It is also referred to as bleach although slightly different from household bleach.  You can purchase this at any retail pool supply store.  Most retailers will supply liquid pool bleach in a 2 ½ gallon jugs which has measurements on the side for easy use.  Simply test your pool water for the necessary amount needed and pour that amount into your pool.  I usually pour liquid Cl in the shallow end of the pool; you can actually see it spread to the deep end of your pool.  The reason I do this is to let it mix with the pool water a little more before heading to the pool pump.  Too much direct swimming pool bleach can cause problems to your pump and motor.  Just because it comes in 2 ½ gallon jugs does not mean that you pour the entire jug without testing Cl levels.  If you are unsure of the amount of to add then go here, testing water chemistry. Ideally, you will add enough liquid Cl to last until you test your pool water again.  Keeping your pool Cl level low but consistent is the best way to keep your pool safe for swimmers.

Chlorine tablets are another popular and easy way to chlorinate your swimming pool. They are also referred to as “Cl tabs” or just “tabs”.  Cl tabs are usually white in color and are shaped like a hockey puck.  The tablets come in various sizes depending on how much pool Cl you need.  1 inch Cl tablets and 3 inch Cl tabs are the most common sizes.  I would use the 1 inch tabs to chlorinate small bodies of water like a bird type fountain or small yard pond.  The 3 inch Cl tablets are better sized for your swimming pool.

The Cl tablets are usually placed in a pool chlorination dispenser.  There are two types of pool tablet dispensers;

1) In-line chlorination tab dispenser which will be located next to your pool equipment and looks like a bank drive through cylinder.  Simply drop appropriate number of tabs into top of tab chlorinator and screw the lid back on tight.  There might be a dial to allow for more or less Cl release located on the tube.  Note:  most people do not have in-line chlorinators.


2) Floating chlorine dispenser is the most common method for tablet chlorination.  This is the small little item we often see floating around swimming pools.  Simply place the appropriate number of Cl tabs into the floating dispenser and adjust the bottom to allow more or less Cl to release. It’s really cheap and simple to use floating chlorination dispensers. 

Should I use Liquid or Tablets?

Actually, you can chlorinate your pool with liquid, tablets, or both at the same time.  There are pros and cons to using each one.  Liquid chlorine is fast acting and almost instant. You can actually add liquid chlorine to a green water pool and almost watch it start clearing up immediately. The problem with the liquid is its shelf life.  It doesn’t last nearly as long as tablets.

Cl tablets last longer. They will keep your pool water chlorinated longer than liquid. The problems with tablets are:

1) They might not be strong enough on their own to keep your pool at a proper level of sanitization.

2) They are made of other chemicals other than just chlorine. They have built in stabilizer.  Stabilizer is good but too much is really bad and can cause other problems in your swimming waters.

This is my pool maintenance tip for chlorination:

I use liquid Cl in all of my pools.  I only use tablets when more pool Cl is necessary.  Example:  I add liquid Cl once a week but the liquid will not last until I return on the following week (usually due to lots of pool use or heat).  I cannot add excessive amount of liquid because the Cl level in the pool would be way too high for safe swimming.  This is when I add a floating chlorine dispenser and add tablets.  In other words, I use Cl tablets to supplement liquid Cl.  Also note that not all pools need tablets.  Some pools can maintain safe liquid Cl levels longer than others.

Keep your pool maintenance simple.

Yes there are other methods and types of swimming pool chlorine. This is the easiest and most cost effective way to sanitize your pool.  I am a pool maintenance professional and that is how I keep my pools sparkling and safe.

You might also have an interest in salt chlorine generators.  This is a process where salt is added to your pool and then a generator converts it to cl.