Anyone who has ever been near a swimming pool knows about chlorine. But even seasoned pool owners may not be familiar with the chlorine alternative bromine. While both are chemical sanitizers used to kill bacteria in swimming pools and hot tubs, there are many differences between chlorine and bromine, and each pool chemical has its strengths and weaknesses. If you are considering which pool sanitizer is best for your pool or spa, this handy guide will tell you everything you need to know about chlorine and bromine.

How Do Bromine and Chlorine Work?

As we mentioned before, both chemicals eliminate contaminants in pool water, but they do it in different ways.

The chemical chlorine is called an oxidizer. Oxidizers work by taking electrons from the contaminants in the water which changes their molecular structure. The oxidation process leaves behind a byproduct called chloramines. Chloramines are responsible for that chlorine smell we all associate with public pools, as well as the skin and eye irritation we sometimes experience after a swim.

Bromine, on the other hand, works by ionization, which means it breaks apart the chemical bonds of contaminants in the water. Using bromine can help to balance the pH levels in your pool, as bromine has a lower pH than chlorine.

Application of Chlorine vs. Bromine

Chlorine can be purchased in granules, tablets, or stick form. Chlorine tablets and sticks are the most low maintenance option, as they can be placed in a skimmer, an automatic chlorinator, or in a floating feeder to slowly dissolve over a period of time.  The ideal chlorine level in a swimming pool is 1-3 ppm. Chlorine pools should be shocked regularly to eliminate chloramines as well as after storms or heavy swimming.

You can purchase bromine in granular form or in the form of bromine tablets. A bromine feeder is recommended for bromine pools, as it does not dissolve quickly enough in a floating chlorinator. The optimal bromine level is 3-5 ppm. Bromine pools and spas can be shocked to reactivate bromine in the water.

Advantages of Chlorine

  • Chlorine is much cheaper than bromine. In fact, the cost of bromine is almost double the cost of chlorine.
  • Chlorine can be protected from UV rays with a stabilizer such as cyanuric acid, while bromine can not. Because bromine dissipates rapidly when exposed to sunlight, chlorine use is much more common in outdoor pools.
  • Chlorine is a more powerful disinfectant than bromine, as it is both an oxidizer and a sanitizer.

Advantages of Bromine

  • Bromine remains more stable at higher temperatures than chlorine, making it a better choice for spas and hot tubs.
  • Bromine remains effective at higher pH levels than chlorine.
  • The byproduct of bromine, bromamines, is still an effective sanitizer, while chloramines from chlorine are not.
  • Because bromamines do not gas off the surface of the water, bromine is considered a better choice for indoor pools that do not receive a lot of direct sunlight.
  • Bromine is less harsh than chlorine on sensitive skin.
  • Bromine in the water can be reactivated with a pool shock treatment.

Should I Use Chlorine or Bromine?

Whether you choose to use chlorine or bromine really comes down to your own unique situation. If you want to go as low maintenance as possible in an outdoor pool, chlorine is definitely the best choice, as it lasts longer in the sun. If you have extra sensitive skin, give bromine a try; you may experience less eye and skin irritation. For a hot tub, bromine is definitely the top choice since it can stand up to high temperatures.

If you need help deciding which sanitizer is right for your pool or spa or if you have questions about any of our pool supplies and equipment, contact Doheny’s today at 800-574-7665 or visit our website at