How many bromine tablets do you need in your hot tub? 

How many bromine tablets do you need in your hot tub? 

Bromine is a popular alternative to chlorine, especially when it comes to hot tubs. It has a few incredible advantages; however, preparing and adding it in the correct quantity is crucial. 

Read this guide to understand how many bromine tablets you need to add to a hot tub. 

The difference between chlorine and bromine 

Chlorine is the more common water sanitizer because of its easy availability and low price. However, in the case of hot tubs, bromine is the better option because of its resistance to high temperatures. 

Chlorine is an effective sanitizer, but it is also quite unstable. While it is prone to quick reduction under direct sunlight (UV rays), it also becomes ineffective under high temperatures, like in a hot tub. 

Here are a few advantages of using bromine over chlorine in a hot tub:

  • Bromine has a lower pH and is less prone to pH fluctuations making it easier to maintain the water balance.
  • It is more stable than chlorine under high temperatures and sunlight.
  • Bromine is gentler on the skin compared to chlorine.
  • It has a mild smell that does not irritate.

On the other side, bromine is also more expensive, needs twice the amount, and works slower than chlorine. 

Pro Tip: If you smell an overpowering odor from your bromine hot tub, it is time to shock it. 

Can you switch between Bromine and Chlorine??

Yes, you can switch between the two, but the process can be tedious. You cannot simply stop using one and add another to the hot tub. Remember, never mix chlorine and bromine because the resulting chemical reaction will be hazardous and can make the water cloudy.  

The best and most reliable method to switch between chlorine and bromine is to drain and rinse the hot tub. Refill it with water and add the sanitizer of your choice. 

You must also purge the plumbing with appropriate hot tub chemicals to eliminate any chances of these two chemicals mixing. Never fill an existing chlorine dispenser with bromine or vice versa. When switching between the two, always use a fresh dispenser. 


Why do you need to add bromine to my hot tub? 

Bromine is a water sanitizer used to kill any microorganisms like algae or fungi in the water. It is also an oxidizer that can be used in high quantities to shock the hot tub to destroy organic contaminants that have taken over the water. Plus, it is also helpful as an algaecide.

Since chlorine is not very effective under direct sunlight and high temperatures, bromine is the only option as it has a slower depletion rate. Additionally, people who are allergic to chlorine or do not like the smell of it are bound to use bromine in their hot tubs.

When do you need bromine tablets for my hot tub? 

There are two situations where you need to add bromine to your hot tub - building a bromine bank and shocking the hot tub. However, a shock is often the first process.

When you drained, cleaned, and refilled your hot tub, you should add a hard dose of sodium bromide to create hypobromous acid. Doing this activates the bromide ions, which will start the sanitization and oxidation process of the water. 

The other reason is to build a ‘bromide bank’ that refers to maintaining the optimal bromide levels in hot tub water. This task is usually automated using bromine dispensers (also called floaters or brominators) by adjusting them to the proper settings. Additionally, you can test the water every couple of days to add bromine for appropriate adjustments. 

You can choose between granular bromine and tablets. 

Granular bromine is the faster method of raising the bromine levels in your hot tub, whereas tablets are suitable for maintenance and a prolonged approach. 

Pro Tip: We have found that crushing tablets and turning them into powder allows the bromine to work faster. 

How many bromine tablets do I need to add to my hot tub? 

It depends upon the current bromine levels in your hot tub water, and the best method to figure it out is a test. You can use pool hot tub test kits to measure bromine levels and be aware that not all kits test for it.

Another alternative is to use an automated digital system like our Sutro hot tub Monitor. It tests your hot tub water three times a day for bromine levels and sends the data and suggestions to your app. 

The optimal bromine levels for a hot tub are between 3-5 ppm (1-3 ppm if your hot tub has an Ozonator). 

The number of tablets will depend upon the volume of your hot tub, the current levels, and brominator/feeder settings. It takes one tablet per 100 gallons of water to maintain an active bromine residual of two ppm. 

If the bromine levels are below two ppm or less, use granular bromine instead of tablets. You can also do this by crushing the pills to a powdered form. 

It is safe to enter the hot tub thirty minutes after adding the tablets to the hot tub. Although, doing a quick test is the best way to decide. 

How many bromine tablets do you need for an inflatable hot tub? 

Inflatable hot tubs also need bromine, and the process of maintaining water balance is the same as a fixed hot tub. The number of bromine tablets will depend upon the current levels of bromine and the volume of the hot tub. That is one one-inch tablet per 100 gallons of water to maintain a bromine level of 2 ppm. 

How often do I need to add bromine tablets to my hot tub?

The answer to it depends upon the current bromine levels of your hot tub water. Since bromine is a sanitizer, it is best to test the levels daily or once every couple of days. You must add tablets in appropriate quantities to keep the bromine levels between 3-5 ppm. 

What to do if you put too much bromine in a hot tub?

Adding too much bromine to your hot tub can result in water imbalance (too low total alkalinity) and skin issues for anybody who uses it. Here’s what you can do to counter it:

  • Do not use the hot tub to let the bromine dissipate naturally. That can take a few days.
  • Expose the water to direct sunlight for some time.
  • Partially drain the hot tub and refill it with fresh water.
  • Use a neutralizer chemical.
  • If the water is unbalance, drain and fill the hot tub with fresh water.


Bromine’s resistance to high temperatures and sunlight makes it an effective alternative to chlorine for hot tubs. The ideal bromine levels in a hot tub fall between 3-5 ppm, and the number of tablets you’ll need depends upon the volume of the hot tub and current levels.

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