You’ve always used chlorine in your pool sanitation and maintenance routine. Perhaps the pool builder or the previous home owner implemented the chlorine sanitation. However, you’ve heard that there are other alternatives to using chlorine as the sanitizing agent in a swimming pool. Maybe someone you know uses bromine, but is bromine better than chlorine in a pool?
Mostly outdoor swimming pools use chlorine, rather than bromine, as the key sanitizing agent to kill bacteria, viruses and other contaminants in water. Even though bromine works effectively to sanitize a pool, chlorine is the sanitizer of choice by the pool industry because bromine cannot be stabilized and is much more expensive than chlorine. Also, if you have a salt water pool, it is easy and inexpensive to produce chlorine from a salt water chlorinator.
Bromine is recommended for spa pools and hot tubs as it works better at higher temperatures, emits less odor and is gentle on your skin.
Table of Contents
What is Bromine?
You may already know from your high school chemistry lessons that Bromine is a chemical element. It lies directly underneath chlorine on the periodic table of elements. So Bromine has similar properties to chlorine. It sanitizes water by killing bacteria, algae and other contaminants.
Chlorine oxidizes contaminants in the water by destroying them whereas bromine ionizes contaminants breaking them apart.
Bromine exists as a red-brown liquid at room temperature and is less reactive and a weaker oxidizing agent than chlorine. However, bromine is still a relatively reactive chemical and toxic.
Is Bromine Better than Chlorine?
Advantages of Bromine
Bromine works better and is more stable at higher temperatures than chlorine. Therefore, use bromine in spa pools and hot tubs.
Bromine produces less chemical odor than chlorine which suits small water pools and spas or people who cannot stand the smell of chlorine.
Free chlorine has a short lifespan in the pool. Once free chlorine combines with contaminants it rapidly loses its chemical reactivity and will no longer work to sanitize the water, whereas bromine has a longer lifespan in the water and keeps the water sanitized for longer.
When chlorine reacts with contaminants in the water it forms chloramines which smell and are ineffective against bacteria. The chloramines disintegrate with shock treatment and dissipate over time. Bromine reacts with contaminants in the water to form bromamines which are still active against bacteria and the smell is almost odorless.
Bromine is less reactive on your skin. People with sensitive skin should use bromine to avoid skin irritation. However, chlorine and bromine have similar chemical properties so if you are allergic to chlorine using bromine will not be an alternative sanitizer.
Bromine does not attack stainless steel fittings whereas chloramines can cause severe corrosion to these fittings especially if chlorine is used in an indoor pool.
Disadvantages of Bromine
Bromine is a less powerful oxidizing agent than chlorine so it’s not as effective as chlorine requiring more bromine to achieve the same level of sanitation.
Bathers really need to wash their skin and swimwear after bathing in a bromine spa or hot tub because the chemical smell tends to stay on your skin and swimwear.
Some people have reported a bromine rash after bathing in bromine treated pools and spas.
Bromine cannot be stabilized with cyanuric acid like chlorine so it’s less useful in an outdoor pool as the UV light will render it ineffective. It would require more bromine to treat the outdoor pool than chlorine. Use bromine in hot tubs and spa pools because of the higher temperature, small volume of water and less reactivity to your skin.
The main disadvantage of bromine is that it costs much more than chlorine. As a result pool owners prefer to use chlorine in a swimming pool but may use bromine in the spa or hot tub.
When pools sanitized with chlorine are shocked they are quickly brought back to the correct sanitation level. Whereas bromine pools require more attention and constant monitoring to achieve correct sanitation levels.
Most pool owners or operators have been trained to use chlorine so they don’t have knowledge or experience with bromine.
Please read our post on Should You Shower Before You Swim?
What Should the Bromine Level be in my Pool?
The normal level for bromine in pool water is 3 to 5ppm.
I recommend maintaining the level around 5ppm for hot tubs and spas.
How do I Add Bromine to my Pool?
Purchase your bromine in the tablet format. Add the bromine to the hot tub using a chemical feeder or floating device. It dissolves more slowly than chlorine so takes longer to disinfect the water but the tablets last longer than chlorine tablets.
When using bromine in a pool you will need to have a feeder device . The bromine dissolves too slowly to use a floating device.
You can purchase granular bromine that can be slowly poured into the spa or hot tub with the water circulating to mix it in.
How to Shock a Bromine Pool
Bromine reacts with bacteria and other contaminants in the water to form bromamines just like chlorine reacts to form chloramines.
Eliminate these bromamines waste products from the pool by shocking the water and filtering contaminates out of the water.
Bromine Rash from a Swimming pool
Some people have reported skin irritation and redness after bathing in pools or hot tubs treated with bromine. While this condition is less common you must be careful that if you have sensitive skin and spend time in these pools that you you’re your body afterwards. If you have a suspected bromine-related dermatitis you must avoid pools and hot tubs using bromine sanitization.
Switching from Chlorine to Bromine
If you have a salt water chlorinated pool you will need to replace your equipment with bromine feeder equipment. You will need to drain the salt water and refill with fresh water.
Otherwise, switching from chlorine to bromine is simply a matter of stop using chlorine and start using bromine. Some pool care specialists say it’s safe to use the same pool water. However, we recommend to change the water to be on the safe side. If you have a hot tub or spa you should change the water every season to eliminate chemical build-ups.
If you have an automatic feeder it will need to be replaced to guarantee there is no chlorine residue to mix with bromine. Mixing of the two chemicals is not safe and may cause a dangerous chemical reaction.
Switching from Bromine to Chlorine
Switching back the other way requires you to drain the pool water and refill to eliminate all bromide ions from the pool. If you have a hot tub or spa you should change the water every season to eliminate chemical build-ups.
Do not mix chlorine into a bromine pool as it will react.
If you had a brominator, replace it with a new chlorine dispenser.
What is Biguanide?
Biguanide (polyhexamethylene biguanide) is a chlorine-free and bromine-free alternative sanitizing product that can be used in swimming pools. It was originally developed for use as a surgical disinfectant but has been developed for the pool industry.
The chemical works by combining with contaminants in the water to produce insoluble particles that are trapped by the filter. Add hydrogen peroxide to the pool to make the product work.
The advantages of Biguanide:
- not affected by pH
- not degraded by sunlight
- unaffected by higher water temperatures
- chemically stable in water
- no chloramines
- no odors
- gentler on skin, hair and eyes
The disadvantages of Biguanide:
- more expensive than chlorine
- not effective as chlorine
- can cause cloudy pool water
- requires hydrogen peroxide which is a bleach
- needs higher concentration than chlorine to sanitize water
- requires special test kit or strips
- needs more filter cleaning
Some pool owners love using Baquacil, which is the most common product on the market that contains biguanide. Many have reported that there pool water is clean, clear and perfect for swimming. It seems to be used more for fresh water above ground pools than other types of pools.
I have over 30 years experience with swimming pool care but I have never used the Baquacil product. So I cannot recommend it either way.
Please read our article on biguanide
Final Thoughts
I have over 30 year’s experience with swimming pool care. I recommend chlorine sanitation for outdoor pools and bromine sanitation for hot tubs or indoor spa pools. Outdoor spa pools adjacent to a swimming pool can use chlorine as the sanitizing agent. Sometimes the pool water spills over from the spa into the pool. So it makes sense to use the same routine for both pools. If the outdoor spa pool is salt water then sanitize it with chlorine .