Bromine vs. Chlorine: What is the Difference?

Bromine vs. Chlorine

Bromine and chlorine are two of the most common pool water sanitizers, and both will decontaminant your pool water by killing bacteria, algae, and other kinds of contaminants.

However, they do it differently and will also differ in other aspects, from effectiveness to how they hold up against the elements.

If you are looking for an effective pool sanitizer and have to pick between them, this guide looks at the two in more detail to give you all the information you need to make an informed choice.

All About Bromine 

Bromine does not exist as a free element in the environment, given how reactive it can be. Instead, it is available in either sodium bromide (NaBr) or potassium bromide (KBr) in seawater.

Bromine comes in tablet and granular form, and it dissolves in water easily like chlorine, meaning you can also apply it using the same methods. However, many people find it easy to add bromine to pools in tablet form using a floating dispenser.

How it Works

Bromine cleans pool water through ionization. Adding it to the pool water will ionize the contaminants and force apart their chemical bonds to destroy them.

As bromine combines with more contaminants, it leads to the formation of bromamines, which can reduce its effectiveness in cleaning the pool water. These compounds have a pretty strong smell, but you can easily remove them from your pool through shocking.

What Makes it a Good Option

While bromamines will form in the long run, bromine remains active much longer after killing the bacteria, meaning you will not need to add it as often as you would with chlorine.

Despite being a potent compound that will kill all kinds of bacteria and other pool contaminants, bromine is surprisingly gentle on the skin. Also, it does not throw the pool’s pH off balance as much as chlorine does, meaning you will have an easier time balancing it.

Bromine also works well at high temperatures. Hence, besides swimming pools, it will also work well for spas and hot tubs.


  • Safer for sensitive skins
  • Produces very little smell
  • Holds up well to high temperatures
  • Makes pH balancing easier
  • Lasts longer in the pool water


  • Can make pool water a little cloudy
  • More expensive
  • Hard to rinse off from the skin

All about Chlorine 

Chlorine is the most common type of pool water cleaning and sanitizing compound. It is a halogen like bromine, and it comes in different forms like liquid, tablet, granules, and powder.

Regardless of the form you choose, chlorine is often relatively easy to apply. Given how common the pool sanitizer is, it should also be relatively easy to figure out other things like the dose you need for your pool as there is lots of information out there.

How it Works

Chlorine will clean your pool water through oxidation. When you add chlorine to the water, it breaks down into different compounds like hypochlorite ion (OCl) and hypochlorous acid (HOCl).

These compounds oxidize the bacteria and other common pool contaminants and hence rendering them useless. They do this by attacking the structures that form their cell walls and destroying the enzymes inside the cell.

However, as chlorine kills pool contaminants, it produces a waste product, chloramines. This waste product is the source of the strong chlorine smell in pools that use this sanitizer. Chloramines also render chlorine less effective at cleaning pool water in the long run.

What Makes It a Good Option

Chlorine is a more common pool sanitizer than bromine, which makes it quite affordable. Therefore, it is will be a great choice when you need to treat larger pools and do it more often.

Chlorine is also an easy compound to stabilize for outdoor pools as you only need to add cyanuric acid (pool stabilizer). Unlike bromine, it leaves the pool water clear since it does not have a cloudy effect.


  • More affordable sanitizer
  • Often easier to apply
  • Easy to stabilize for outdoor pools
  • Does not make the water cloudy


  • Can have a strong odor
  • Not suitable for sensitive skins
  • Requires more frequent application
  • Makes pH balance harder

Bromine vs Chlorine


There are different ways of measuring the effectiveness of a pool cleaning agent. However, the reactivity rate is often the most reliable parameter to use. Reactivity rate is how fast the compound kills the pool contaminants.

Bromine is a highly reactive compound, but it works much slower than chlorine. While it will still kill the contaminants, it requires more time.

Chlorine rips through all the pool contaminants super-fast, and hence the pool water should be clean and safe to use almost instantly.

But, it is also worth noting that bromine has a lower pH, meaning it is less likely to kick your pH off balance as chlorine often does.


Both bromine and chlorine are pretty harsh chemicals that require maximum precaution when handling. However, chlorine poses a greater risk to your health and safety, and it is harsher on the skin, eyes, and hair if too much of it is in the pool.

Over time, the accumulation of chloramines in the pool can also lead to breathing problems and even trigger asthma attacks.

Although bromine is gentler on the swimmers, it is often harder to wash off the skin after a swim, which can be annoying.


Bromine is more expensive than chlorine, which is why it is not as commonly used as the latter. Different factors determine the actual cost of using either chemical.

However, it will cost at least $1,000 every year to maintain your 20,000-gallon pool using bromine, while using chlorine costs less than $600 to maintain the same pool size.


Whether you use chlorine or bromine to treat your pool water, you need to get the dosage right for the best results. The good news is that most companies that sell both will provide clear directions on the dosage to use.

When using chlorine, the recommended dose is between 1 and 3 ppm (parts per million), while it is 3 to 5 ppm for bromine. The best idea is always to add the maximum recommended dose. Although you will need to use more bromine than chlorine, you will add it less frequently.


Now that you know how these two pool chemicals differ and how they work, picking between them should be a breeze. But, regardless of what option you opt for, make sure you add the correct dose and maintain it there through regular top-ups.

Also, whether you use bromine or chlorine, make sure you never mix the two, use the same feeders for both, or even store them next to each other.

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