Bromine vs Chlorine: When to Use Them in Your Swimming Pool

Even the newest swimming pool owners among us will have some inkling as to the importance of ensuring pool water is kept clean. It likely comes as no surprise that we would recommend putting swimming pool chemicals and water sanitisers at the top of your list when thinking about how to properly maintain your pool year-round. 

But which sanitisers are the best for keeping water pristine and safe to swim in? The two you’ll likely be choosing between are chlorine and bromine. Chlorine may seem like the obvious choice, as it’s more well-known, but there are benefits to each which are worth considering. 

what chemicals do you need for a swimming pool

What’s The Difference Between Chlorine and Bromine? 

Chlorine and bromine are both chemicals used to sanitise swimming pool or hot tub water, preventing the growth of algae and bacteria – something you certainly don’t want when taking a dip. 

Both do essentially the same job, if in slightly different ways. Chlorine is an oxidiser whereas pool bromine works via ionisation. These varying processes mean that the contaminating molecules in the water are broken down differently. The important thing to know is that both chemicals effectively remove bacteria from your water.

More tangible differences can include cost, how they affect swimmers’ skin and the form they can come in. 

A woman floating in a pool

What Does Chlorine Do in a Pool? 

Chlorine actively destroys contaminants by changing the offending molecules' structure. During the oxidation process, chlorine will dissolve in the water, creating a waste byproduct known as chloramine. 

It is chloramine that gives chlorine-treated pools that distinctive smell.

You will need to use chlorine (or an alternative) as part of your regular pool maintenance routine, checking the levels to ensure it can do its job. 

What Does Bromine Do in a Pool? 

Bromine breaks apart the chemical bonds of the contaminants and will remain active in the water, even after it has worked on the contaminating particles, continuing to remove any unwanted bacteria when reactivated by a shock. 

Like with chlorine, a byproduct called bromamine is produced, which is often considered to have fewer side effects than chloramine.

Is it Better to Use Bromine or Chlorine? 

Using one or the other is not really a question of which is better – both chemicals will effectively sanitise your water, which is the main priority – it is a question of which is better for your circumstances and needs. 

You will only need to use either chlorine or bromine at one time, not both together. 

A swimming pool with lanes

Why Choose Chlorine for Your Pool? 

Chlorine comes in several forms, two of the most common being granules and tablets. These application methods are convenient and low maintenance, making it fairly easy to get the dosage right. 

Chlorine tablets or granules?

As well as being the more well-known chemical, chlorine tends to be cheaper than bromine. It also dissolved faster than bromine, working to kill bacteria more quickly. This may also mean you’ll need to add more chlorine to your water more frequently as it doesn’t remain active. 

UV rays from the sun will cause both chlorine and bromine to evaporate, meaning the chemical level in the water is insufficient and won’t kill off contaminants. However, chlorine can be protected from the sun by a stabiliser like cyanuric acid – the same cannot be said for bromine. This often means chlorine is the popular choice for outdoor pools. 

Some swimmers’ find that when the dosage is too high, chlorine can cause skin irritation and bromine is often touted as being gentler on sensitive skin. However, remember that using the correct dosage of either chemical should help you avoid issues with skin or eye irritation. 

Why Choose Bromine for Your Pool? 

Bromine is often posited as a ‘chlorine alternative’ but it can be a valid and useful sanitising option in its own right. 

Like chlorine, bromine is available in granule or tablet form, with tablets in a floating dispenser often considered to be the easiest application method. 

One of the main reasons you would opt for bromine is because of its stability. Bromine is more stable than chlorine (with the exception of in direct sunlight) as it works more slowly over a longer period of time. This means it is usually a better option for water of higher temperatures; i.e. your spa or hot tub

Bromine also has a lower pH level than chlorine, meaning your other chemicals will be kept more balanced and you won’t have to keep readjusting them as frequently as you would when using chlorine. These features can help make bromine more cost-effective.

As already stated, bromine is usually considered to be gentler on skin and can even be a better choice for those with asthma. Bromine also does not produce as strong of a chemical smell as chlorine.

Can You Mix Bromine and Chlorine? 

Do not be tempted to combine chlorine and bromine or use both at the same time. If mixing the chemicals, you run the risk of unforeseen chemical reactions. There is just no need to use both at once – proper use of one or the other will see your water sanitised efficiently. 

Two rubber ducks on the side of a pool

Ultimately, which chemical you use will come down to your circumstance and which benefit is most important to you. Either way, you must keep on top of your pool maintenance and ensure you’re using the right combination of swimming pool water treatments. 

Whether it’s chlorine, bromine or any other essential chemicals you’re after, we stock everything you could need here at 1st Direct Pools. 

swimming pool sanitisers