What is Bromine?

What is bromine and what does it do? Bromine is grouped into the same family of chemicals as its popular counterpart, chlorine. This group, known as halogens, are known for attacking microorganisms like bacteria and using oxidation to eliminate them. This process is what makes chlorine and bromine the two most popular choices for pool and spa sanitation.

There are a few reasons people choose bromine over chlorine.

  1.  Many find its odor far less offensive than chlorine.
  2. It seems more mild on people’s skin and eyes if they are easily irritated by chlorine
  3. Bromine is more stable at high water temperature, making it easier to maintain.
  4. Unlike chlorine which loses its ability to sanitize after being combined with waste, bromine can be reactive with a non-chlorine shock treatment.

Forms of Bromine

Bromine is popular in three different forms: tablet, brominating concentrate, or as administered through a floating or inline cartridge type mineral system.


You can test bromine levels to make sure they are high enough twice a week either using test strips or a more effective drop test kit.

No matter which way you’re testing or how it’s being administered in your spa, if it is maintained at correct levels it will work as a great sanitizer to keep your water crystal clear.

Maintenance needs of a given spa will vary depending on the usage of the tub, both the frequency and how many people use it on a regular basis. Here are some basic guidelines to keep in mind when caring for your spa.


  • Bromine tablets being used in a residential spa should maintain a 2-4 ppm total bromine residual.
  • Tablets used in a commercial hot tub should maintain a 4-6 ppm total bromine residual.
  • If you’re starting with a freshly filled hot tub* and using tablets, fill up the floating feeder with them as instructed by the manufacturer. Shock your water with either a brominating or chlorinating concentrate in order to eliminate unwanted compounds and create a sanitizer residual. You will then want to adjust the rate of flow from the tablets in your feeder. For the first week, test the water frequently and shock as needed to get the correct bromine residual established in order to maintain it.

Bromine Concentrate

  • The bromine concentrate being used should maintain 3-6 ppm total bromine residual.
  • If you’re doing a fresh fill and using a bromine concentrate, add 2 teaspoons per 400 gallons of fill water with the pump running. For the first week, test the water frequently and add concentrate as needed to maintain its levels.

Mineral System Cartridges

  • Spas using bromine along with a mineral system should maintain a 1-2 ppm residual of bromine and follow the instructions given by the manufacturer.
*When refilling your hot tub, make sure you have adjusted the alkalinity, pH levels, and calcium hardness before adding the bromine.
Bromine: Pool Sanitizer FAQs

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