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How Many Bromine Tablets to Put in a Hot Tub? – Pro Guide

how many bromine tablets to put in hot tub
Written by Kai Michel
Last Update: August 10, 2023

Bromine is used to sanitize hot tubs and spas. Keeping water clean and healthy requires some sort of sanitizer and preventing bacteria from breeding.

Bromine is a very effective sanitizer, and I use it in my own hot tub. Here we will explain how you can use bromine effectively and safely in your hot tub too.

How Many Bromine Tablets to Put in a Hot Tub?

How Many Bromine Tablets to Put in a Hot Tub

Up to six tablets can be held in some bromine dispensers. If you don’t want your bromine levels to rise too high, start with 1-2.

It’s good to add as many as six 1-inch tablets at once to one of the better designed floating dispensers. If you are just adding the tablets to the water without any floater, start with 2 tablets. It is easy to add more when needed.

Adding more bromide to a spa with a large area might be necessary but start cautiously since it can be complex to try and lower the levels when you add too much.

What Is the Purpose of Bromine?

Bromine is a popular alternative to chlorine, which is typically used in swimming pools and hot tubs.

Chlorine has some issues that bromine does not have:

  • Chlorine is more drying and can cause irritation, including rashes, redness, and itching to some people. Bromine is gentler on the skin.
  • The lower pH of bromine can help you maintain your water balance
  • As bromine levels are more stable, it will last longer and not need to be topped up as often as chlorine, it keeps its level more consistent

Testing Your Bromine Levels

A spa water usually has varying levels of bromine based on how frequently it is used and how much time it stays uncovered in the sun and in the dew. Spa water should have a bromine concentration between 1 and 3ppm (parts per million).

You can use a bromine water test kit provided by your spa dealer to determine the current level of bromine in your hot tub water. Ask the dealer if you have any questions about how the water is purified. Use the instructions that come with the kit.

Using a bromine meter, you can estimate exactly how much bromine should be added, or how much it may need to be diluted. Every week, you should test your water to ensure that it is as pure as possible.

Test strips can be used to determine if the pH level is between 7.0 and 7.4. They are often used in conjunction with a bromine test strip to determine pH and total alkalinity. Depending on its level, the water can be balanced by adding either a pH+ or a pH- increaser or reducing agent.

How Long Do You Have To Wait After Adding Bromine to a Tub?

The amount of bromine tablets that are exposed to water and how large they are determine how fast they dissolve.

The whole of a 1-inch tablet, for instance, can dissolve in about 1-3 weeks if fully submerged in water. As a result, a broken or crushed tablet will disintegrate within a few hours.

The tablets can take around 2-3 months to dissolve in a dispenser, assuming the lowest setting is used. As a spa owner, I have found this method to be the best way to dissolve the tablets at a controlled rate.

What if You Have Added Too Much Bromine?

Several options can be tried if your bromine levels are really high (over 10 ppm):

  • Allow the levels to drop naturally. This is the most convenient if you won’t need it for a few days. You’ll find the levels will gradually go down on their own if you take the bromine floater out and don’t add any more shock.
  • Open the spa. Let the cover hang off for an hour or so. Sunny days are best. Bromine is broken down faster by evaporation and sunlight.
  • In some cases, replace the water. Replace the water you removed. To dilute excessively sanitized water, use fresh water.
  • Neutralize If your bromine levels are too high, products like Thio-Trine Neutralizer by Applied Biochemist can help. They typically come with instructions for large pools. Since spas are smaller, you will only need a very small amount.
  • All the water needs to be replaced. There is no other option. You might be better off with new water and a fresh start if you’re still having difficulty getting your levels in an acceptable range.

What if the Bromine Level Is Too Low?

What if the Bromine Level Is Too Low

1. The dial setting should be checked

The dial of a salt generator, for example, can be turned up to increase the amount of salt dispersed. Make only one setting adjustment per day to ensure the desired level of chlorine or bromine is maintained.

Monitor the water for 24 hours after making the adjustment. Do not alter the setting once it is found to be optimal. The water should be shocked when conditions are abnormal (heavy use or rain).

2. Increase the amount of chlorine/bromine being used

In the case of a floater, make sure there is enough water to reach the chemical by filling it to the top. Chlorine or bromine increases the output as it is wetted more. Adding more chemicals or increasing their frequency may be necessary if spoon feeding chemicals.

3. Make sure your water is properly balanced

Proper sanitization depends on a balanced water supply. Even if there is enough chlorine in the water, it will not be effective if the pH is off. The good thing about bromine is that it is less sensitive to pH changes.

4. Look for the presence of algae

Chlorine or bromine can be used quickly to kill algae when the spa is about to be occupied by it. Bring back your chlorine/bromine levels and shock your water with a chlorine/algaecide.

If the spa is outdoors and uncovered, do not use fertilizers.

5. Use an algaecide

Chlorine works very hard to prevent algae from growing in the water but it may appear to be completely chlorine-free. Keep your pool’s chlorine/bromine level at the desired level by using an algaecide or by shocking the pool.

6. Drain and refill your spa

It may be difficult to maintain the water in the spa if you haven’t drained and refilled it in three months. Start over with fresh water after draining the water and cleaning the surface and filter

7. Check if the test strips and kits are expired

The average test strip is only good for 12 to 18 months. There is a risk of inaccurate readings after that period. Additionally, placing wet hands inside the container could contaminate the test strips, resulting in an even shorter lifespan.

Is It Possible to Change From Chlorine to Bromine?

The sanitizer in a hot tub can be switched from chlorine to bromine. it is easier making the change from chlorine to bromine instead of the other way around. Whenever you add chlorine, stop and replace it with brominating tablets.

A bromide bank will gradually be built up as the tablets dissolve. This residue bromide will be converted into bromine when the spa is next shocked.

Is Mixing Chlorine with Bromine Together Safe?

Both chemicals should not be mixed directly. With bromine tablets, you should get a new floating dispenser if you used one with chlorine. By doing this, you can ensure that chlorine isn’t left behind. This doesn’t work the other way around.

In spas that already have bromine, adding shock will reactivate this bromine. However, the spa will still be bromine. Without a complete drain, clean, and refill, it’s not possible to remove all bromine from the water. Cleaner such as Ahh-Some can be used to flush the plumbing lines.

Tips to Put Bromine Tablets in a Hot Tub

  • Whenever you refill your hot tub, add sodium bromide to the water
  • Once the spa has built up, use spa shock
  • Spa shock should be used following the initial shock just once a week
  • The floating dispenser should be filled with bromine tablets As a preventative measure against bromide and bromine poisoning if they are picked up by children or pets and eaten
  • Having an extremely high bromine level in the water is a less common cause of a zero bromine reading


1. How long to wait after adding bromine to the hot tub?

Ans. Don’t forget to test the water after adding the bromine tablets and wait around 30 minutes afterward. To make sure your hot tub is safe after adding chemicals, always refer to the manufacturer’s guidelines.

2. Is it a good idea to use a floating dispenser in the spa?

Ans. Maintaining the bromide levels in your spa between water changes is easy with a floating bromine dispenser. Add bromide boosters you do not use one. The brominating tablets can also be added directly to the skimmer basket if your hot tub has one.

About the author

Kai Michel

Hello, this is Kai, addressing homeowners in need of some help with their home renovation projects. I’ve worked on numerous toilet repair projects over the years that incorporated a wide variety of tasks, from repair to renovation and maintenance. Besides acquiring a degree on the legal codes and procedures, I gathered vast insights into bathroom settings, toilets, showers, fittings, and other household appliances, fixtures, and components. This helps me guide my clients through their home improvement and interior development plans. Since maintenance is my area of expertise, I can assist people in all phases of the actual ‘improvement’ process. To get my messages even further, I contribute to this site through my blog posts. Check my content here for expert suggestions!

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