Hot Tub Bromine


If you’re new to the world of hot tubs, you may be confused by all the different types of sanitizer. If you’re a swimming pool owner, odds are you’re most familiar with chlorine. While chlorine can work in hot tubs, it’s less stable in the high temperatures and can be trickier to keep balanced than some other options. For spa sanitation, bromine is an excellent choice. In this post, we’ll try to help take the guess work out of hot tub bromine.

Bromine and chlorine are both in the same chemical family known as halogens. They are excellent at attacking microorganisms like bacteria, using the process of oxidation which attacks bacteria’s cell walls and destroys the structures inside these cells, rendering them harmless. That oxidation process is what makes chlorine and bromine ideal for pool and spa sanitation, although (as previously stated), bromine is much more stable at high temperatures.

Bromine is also more popular for hot tub sanitation than chlorine for a few additional reasons:

  • Many find its odor less potent than chlorine.

  • It is mild on people’s skin and eyes, particularly if the bathers are already sensitive to chlorine.

  • Unlike chlorine which loses its ability to sanitize after being combined with waste, bromine can be reactivated with a non-chlorine shock treatment.

Just like any form of sanitizer, bromine can have its drawbacks:

  • Although it’s mild in odor in comparison to chlorine, it’s in no way odor-free.

  • Some people may have a sensitivity to bromine the same way some people are sensitive to chlorine.

  • It can dry out your skin, particularly if you have a proclivity towards eczema.

  • Bromine degrades when exposed to sunlight.

  • Direct contact may discolor jewelry.

Bromine is commonly distributed in three different forms: tablet, brominating concentrate, or in a floating cartridge/inline cartridge system. Each have their benefits and draw backs.


You should test your sanitizer levels twice a week either using test strips or a drop kit, more often if you have a high bather load or you have a problem with keeping your water balanced. Here are the guidelines for what you should be looking for depending on the type of bromine you use:

Tablets—used in a residential spa, should be maintained between 2-4 ppm total bromine residual. In commercial tubs, that number should be between 4-6 ppm.

Tablets should be added to a freshly filled hot tub after adjusting your alkalinity, pH, and calcium hardness. ALWAYS adjust those elements first before adding a sanitizer to your hot tub water. Fill your feeder with them as instructed by the manufacturer. Shock your water with either a brominating or chlorinating concentrate in order to clear the water of unwanted compounds and create a sanitizer residual. Then adjust the rate of flow from the feeder. Test the water frequently during that first week and shock as needed until you get the bromine to read in the target area.

Concentrate—bromine concentrate should be maintained between 3-6 ppm total bromine residual.

If you’ve just refilled your hot tub and are using a bromine concentrate, add 2 teaspoons per 400 gallons of fill water with the pump running (or according to the manufacturer’s instructions). For the first week, test the water frequently and add concentrate as need to maintain proper chemistry.

Mineral System Cartridges—spas using bromine alongside a mineral system should maintain a bromine residual of 1-2 ppm. Be sure to follow manufacturer’s instructions for this choice in sanitizer.

 We hope you get your hot tub up and running with bromine as soon as you receive your pool chemicals. It really is a great way to keep your water clean and sanitized.
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