Chlorine: Pool Sanitizer FAQs

Chlorine is a popular sanitizer for swimming pools. It's relatively inexpensive and highly available, as well as being a very effective chemical for killing bacteria. Let's take a look at a few key chlorine facts to see why chlorine is such a popular pool sanitizer.

What Is Chlorine?

Chlorine, like bromine, is part of the halogen family of elements. Like all halogens, chlorine is a base, which means it can react with hydrogen ions. This chemical property of halogens allows them to interact with impurities in water, killing bacteria to keep pool water clean and safe. The chemical properties of chlorine vs. bromine can affect your choice for which pool chemical to use to maintain your swimming pool.

Chlorine Advantages

Chlorine is an extremely powerful killer of bacteria. It's possible to stabilize chlorine to prevent it from breaking down when exposed to UV radiation, such as in sunlight, by adding cyanuric acid to the water. When combined with cyanuric acid, chlorine can remain stable over a period of many days, whereas bromine breaks down quickly in an outdoor pool.

Chlorine comes in tablet form, which means you can gradually add it to your pool to keep the concentration relatively constant. Simply place a tablet in your pool skimmer to release the chlorine at a controlled rate. Chlorine also comes in a quick-release form that you can use to shock your pool with a large dose of it all at once. Shocking your pool is a good way to deal with algae in the water.

Finally, chlorine is less expensive than bromine. As chlorinated pools are more common than brominated pools, chlorine is also more widely available for purchase.

Chlorine Disadvantages

Pool chlorine also has some disadvantages. First, it's not effective at pH levels above 7.8. Therefore, you need to test the pH of your pool regularly and add chemicals to bring the level down if it's too high.

Chlorine forms strong-smelling, volatile chemicals called chloramines. When chloramines become airborne, they create the "chlorine smell" that seems to hang around indoor pools. Some people experience eye and lung irritation as a result of these chemicals hanging around in the air. Bromamines, the chemicals produced when bromine reacts with impurities in water, generally remain in liquid form, where they're less likely to cause irritation.

Total Chlorine vs. Free Chlorine

When checking chlorine levels in your pool, you need to measure the amount of free chlorine. This is the amount of chlorine that's available to kill bacteria and combine with other impurities. Combined chlorine is the amount of chlorine that has already combined with ammonia and nitrogen compounds in the water to form chloramines. Total chlorine is the amount of free chlorine plus combined chlorine. If the total chlorine level is too much higher than the amount of free chlorine, you may need to shock your pool to remove chloramines and increase the amount of free chlorine available.

Chlorine is an effective sanitizer for most swimming pools. Some people choose to use bromine instead, as it doesn't produce the "chlorine smell" that's sometimes a problem with indoor chlorine pools. However, the great advantage of pool chlorine is that it resists breaking down in bright sunlight, which makes it a very suitable choice for outdoor swimming pools. Test the amount of free chlorine in your pool regularly to ensure that it remains within a safe and effective range.