What’s Best To Use For Your Pool: Bromine vs. Chlorine

By June 15, 2021Pool Safety

Written by Michael Dean and published on https://poolresearch.com/

What are the differences between bromine and chlorine? Which is a better choice to disinfect your pool or spa?  Don’t worry, there won’t be a quiz today. Instead, we’ll answer those questions and more to help you make the most informed decision about how to keep your pool and spa sparkling clean!

Both bromine and chlorine are chemical compounds that serve a similar purpose: they decontaminate pool and spa water by killing off bacteria. However, these chemicals differ in the way they clean, react to temperature and interact with skin. If you’re considering bromine vs chlorine for use in a pool or spa, our guide will help you choose the option that’s best for your situation.

Bromine vs. Chlorine: What’s Best for Your Pool

With no sanitizer in your pool or spa, you’re sitting in a tub of pollutants. For clean water, you need to apply a sanitizer. Remember, your water has exposure to anything floating around. A pool sanitizer kills bacteria. It inhibits algae, viruses, and other contaminants.

The most common sanitizer used to clean water is chlorine. But there’s also bromine. What’s the difference? Which works best? Let’s find out. What follows is a look at bromine versus chlorine and what’s best for you.

How They Work

Let’s start with some basic overviews for each chemical and how they fit into your pool chemistry.


Chlorine is a building block of matter. It’s a natural chemical element scattered over the globe, mostly concentrated in salty oceans. It’s a critical nutrient for animals and plants.

When extracted, we use chlorine to clean drinking water. Chlorine is a killer of pathogens by destroying chemical bonds in contaminants. Disinfectants use chlorine compounds in a process that exchanges compounds like atoms. It attacks harmful enzymes in bacteria and viruses.

When chlorine confronts enzymes, a chemical reaction occurs. Chlorine replaces hydrogen atoms. The molecule either falls apart or changes shape. Unable to function properly, the failure of enzymes leads to cells or bacteria dying.


Like chlorine, bromine is another naturally occurring element. At room temperature, it becomes a liquid. It dissolves in water with a bleach-like odor. Like chlorine, bromine lurks in seawater and the earth’s crust.

Industries like sanitation and agriculture. It is also used as a pool sanitizer. One major difference between chlorine and bromine is you would not use the latter to sanitize drinking or cooking water.

There are plenty of uses for bromine. It’s an oxidizer, sanitizer, and algaecide. Many spa, pool, and hot tub owners use bromine instead of chlorine. They appreciate that, compared to chlorine, bromine works better under warm temperatures.


How well does each of these work? Let’s dive in.


Disturbing as it may sound, our inbound water gets exposed to everything from bacteria and parasites to mold and viruses. These elements build on water mains and in storage tanks. They produce disagreeable odors and tastes in our water.

Chlorine is instrumental in eliminating the likes of slime bacteria, algae, and other pollutants that grow in our water systems. Chlorine is such an effective deterrent to bad water, the EPA has regulations for treating water with chlorine to kill germs that may reach our taps.

This is why many pool techs and owners turn to chlorine.


Bromine neutralizes harmful pollutants in water. It does so continuously and for significant amounts of time. This is a great advantage over chlorine as the bromine application isn’t needed as much to disinfect as chlorine.

Chlorine contains bleach. It has a very distinct smell and can be irritable to the skin. Bromine is widely known for having an imperceptible odor. Pool water treated with bromine has fewer reports of bad eye or skin reactions. As bromine has no bleach, water has less effect on clothes.


The more stable the sanitizer, the safer it is to use. Is chlorine or bromine more stable? Let’s find out.


Chlorine is safe. It keeps us healthy, killing germs in the water. Chlorine is a risk when misused. Do not mix chlorine with other chemicals. Compounds like will create toxic vapors.

Chlorine developed for pool and spa waters protect us from germs and bacteria. It’s effective against health conditions like diarrhea or swimmer’s ear. The CDC says pH and chlorine make up the first line of defense against contaminated waters, which we agree with.


Bromine remains stable at higher temperatures than chlorine will. The chemical composition of bromine reacts differently than chlorine and ends up doing a more efficient cleaning of water in hot temperatures. This is why there will be fewer applications of the solution than chlorine.

Also, bromine doesn’t have that strong scent. It’s gentle on the skin and works with vinyl liners. Bromine is fast becoming a preferred alternative to chlorine but it is also the more expensive of the two options.

How Much To Use

How much should you use to disinfect your pool? The answer is a bit different for chlorine and bromine.


It’s advised you should manage one and three ppms (parts per minute) in your pool. Take the number of gallons in the pool and multiply it by 0.00013 ounces per gallon to know how much chlorine to use.

Always remember before adding chlorine, use a test strip to test the current chlorine level. Too much chlorine can increase harmful chemicals in the water. It can also generate gases as the water — oversaturated with chlorine solutions — evaporates. The gases can cause severe discomfort in the eyes and nose.


As bromine is popular for withstanding greater temperatures than chlorine, it’s not surprising it’s the preferred sanitizer for hot tubs and spas. Compared to bromine, chlorine requires daily maintenance for balance. Bromine has a greater efficiency over a wider pH range compared to chlorine.

You shouldn’t use bromine if levels are low or if bromine levels are too high. There is no UV degradation protection if using this compound. You’ll need a spa cover to safeguard the water. But if managed properly, bromine is a great sanitizer, keeping hot tub water free from macrobiotic bacteria. The routine will be simpler than chlorine balance.

Chlorine vs. Bromine: Health Concerns

As long as you use these elements in proper amounts, bromine and chlorine are safe. Of course, people can react differently to them.

Chloramines, born of chlorine and ammonia, are disinfectants that treat water. Chloramines are a longer-lasting disinfectant. Chlorine has scalability and low cost.

Chlorine can create difficulty breathing, sore throat, wheezing, coughing, chest tightness, eye and skin irritation, and other conditions. Most conditions result from ingesting heavy amounts of chlorine into the body, which you’re likely at low risk of in a pool.

Bromine has a long shelf life and dissolves slowly. In some applications, it’s activated with an oxidator. The solution will last longer than chlorine.

If your water’s outdoors, you’ll need a cover as bromine has no defenses against UV light. UV light kills bromine faster than it does chlorine.

When not used safely, breathing in bromine gas can give you a headache, watery eyes, irritate mucous membranes. It can disorient you or make it difficult to breathe. Getting bromine gas or liquid on the skin can cause irritation and even burns.

Safety Tips for Handling Chlorine and Bromine

Take a sample of your water with you to the shop. The dealer will check the acidity and help you make the best purchase.

For chlorine, fill a container with a blend of chlorine and water. Pour the mixture into a second container and add water. Get the granules to dissolve by stirring the mixture.

Pour in the chlorine mix while walking along the pool edge, dispersing evenly. Wait a few hours and look for residue towards the pool floor. Vacuum the residue.

For bromine, you need to generate a sufficient level of bromide ions in the water. Regular shocking, or oxidation, will convert bromide to bromine.

Follow the label instructions, adding sodium bromide to your spa. After building up your bromide bank, use spa shock at least once a week to activate the bromine.

When preparing your sanitizer, work in an open, ventilated space. Use PPE. For storage and handling, take a look at my guide on swimming pool chemical storage.

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How to Use Chlorine and Bromine Granules

Have your PPE: goggles, gloves, and mask.

Fill a container or bucket halfway with warm water. We suggest you use water from the pool, spa, or hot tub. Depending on the size of your pool, add one to two pounds of granules to the water. Stir it with a stick. It’s best to use wood. Anything else gets bleached.

The pump has to circulate the mixture. Otherwise, it settles on the pool floor. Turn on the pump and remove the skimmer cover. Slowly add the chlorine mixture into the skimmer while avoiding spillage. Put the skimmer cover back. Don’t use the pool for a few hours so that the chlorine disperses sufficiently.

From bromine, turn on the pump and remove the cover. Soak the filters overnight with a filter cleaner. While it tries, get to work with your granules.

Fill your hot tube with fresh water. Check the pH for balance. You can add 60 grams of bromine granules for every 2.5 gallons of water. Wait for the level to drop to between three to five milligrams per liter before getting into the tub.

How to Use Chlorine and Bromine Tablets

To safely use tablets, you need to know the volume of your pool. Use our pool volume calculator to get an estimate. Round your volume up to the nearest five-thousandth gallon. So, if your rounded number is 10,000 gallons, you’d use two chlorine tablets. (These estimates are for three-inch tablets.)

Apply your bromine tablet treatment at least once a week. For pools, add at least 17 tablets for every 10,000 gallons of water, or as needed.

You want to manage levels of bromine residue of two to three ppm at all times. For your spa or hot tub, use three tablets for every 300 gallons. The best way to do this is with an automatic brominator or floating tablet feeder.

No one wants to sit in a tub of pollutants. Pool sanitation will be instrumental in cleaning your water. When you’re looking at chlorine versus bromine, use info like the material above to know exactly what’s best for your pool.

Original post here https://poolresearch.com/bromine-vs-chlorine/.

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