Bromine vs Chlorine In Your Pool or Hot Tub

Should you use Bromine or Chlorine to sanitize your pool or hot tub? You probably know that both chlorine and bromine can be used to clean pool and hot tub water but, which is better and what's the difference?

Let's start with a little chemical background. This will take you back to 10th grade Chemistry class. Bromine and chlorine are two of the six halogens. Halogens are non-metallic and will produce salts when broken down. Both Chlorine and bromine are used for water sanitization. 

All halogen elements are oxidizing agents, meaning that they will "steal" or "consume" electrons. This process is known as oxidation. Both chlorine and bromine oxidize and destroy contaminants like bacteria or algae.  

Which is best chlorine of bromine?

We already know that both chlorine and bromine neutralize pathogens in your pool and hot tub water. But, is one more effective than the other? Let's do a little comparison. 

Cost - chlorine vs bromine

The most cost effective way to sanitize your water is using 3 inch chlorine tablets. They last a fairly long time and are formulated with cyanuric acid which stabilizes the chlorine, slowing it's release and breakdown. If you purchase chlorine tablets in bulk, this sanitization method is about 40% cheaper than bromine. 

Lasting Effectiveness - chlorine vs bromine

The reason cyanuric acid is added to chlorine tablets is for stabilization of the chlorine. Let's take liquid chlorine for example. It's great for quickly raising chlorine levels and effectively sanitizing your water. However, the concentration will quickly decrease and more will be needed . 

This is not the case with bromine. Bromine has a unique property of reactivation. The bromide left over as bromine breaks down can be reactivated by add a bit of chlorine shock. Essentially, this means that you can restore the bromine again and again. On the other hand, once chlorine is broken down it becomes permanently inactive. 

In terms of lasting effectiveness, bromine definitely has the better staying power when it comes to sanitization. 

Pure Sanitizing Power

Strictly in terms of power, chlorine is a quick killer. For example it is very effective in treating and killing algae that causes green, cloudy water. Bromine however, has a much larger sanitizing window and is effective in more water conditions than chlorine. 

As the pH of you water drifts the activity of chlorine can be greatly reduces. As pH increases above 7.6 chlorines effectiveness decreases. This means you must control your pH in order to control the killing action of your chlorine. Bromine, on the other hand, will continue to sanitize your water even as pH swings. As a result, bromine may be more effective in destroying viruses and bacteria. 

Water Temperature - chlorine vs bromine

Chlorine will become less stable as water temperatures increase. In fact, once temperatures exceed 100 degrees chlorine will begin to gas off releasing the chlorine from the water into the air. Bromine will remain stable at high temperatures and concentration levels will remain constant. 

This is the primary reason bromine is used to sanitize hot tube while chlorine is great for pools. Well, that and the smell. As chlorine enters the air it can have a very strong smell. This can be overwhelming in indoor spaces. Bromine is basically odorless. 

Can You Mix Chlorine and Bromine

It is not recommended to mix chlorine and bromine. It can result in a toxic chemical reaction. However, as mentioned above, small amounts of chlorine shock can be add to a bromine treated hot tub for reactivation purposes. Otherize, mixing is not a good idea. 

The Wrap Up

In conclusion, chlorine is a great sanitizer for swimming pools and bromine is better suited for hot tubs and indoor pools. The most important part of maintaining a healthy pool and spa is understanding your water chemistry. It is important to test your water regularly. Your water will respond to everything you do. It's a good idea to test, make necessary changes, and test again. Having a pool or hot tub is like having a Zen garden. The devil is in the details.

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