Should You Use Chlorine or Bromine to Sanitize Your Hot Tub?

Should You Use Chlorine or Bromine to Sanitize Your Hot Tub?

All hot tubs need to be sanitized/disinfected before use to ensure they are safe to get in.  There are 3 main ways to do this, we refer to them as “protocols":

  1. Chlorine
  2. Bromine tablets
  3. Sodium Bromide with shock
  1. Chlorine - in this protocol, granular chlorine, usually Dichlor (not Trichlor) is added to the hot tub to keep it sanitized.  The chlorine levels are monitored just like they are in a pool, and Chlorine is added when the levels are too low.  Chlorine levels drop over time, or as people use the hot tub and the Chlorine gets "used up”.


  • Chlorine is relatively cheap
  • Chlorine is a better oxidizer (than Bromine) - it breaks down organic waste from nature and bathers in your water very effectively, so your water may look cleaner


  • Chlorine is not as effective at higher pH levels - so you have to be good about staying on top of your pH level
  • Chlorine gives off a stronger smell (than Bromine) when it’s working, and some people find it more irritating to their skin
  1. Bromine Tablets- in this protocol, Bromine Tablets are added to the hot tub, usually in a floater that holds the tablets and allows them to dissolve slowly over time (a week or two).  Bromine levels drop over time, and as people use the hot tub, just like with Chlorine.


  • Bromine odor is less offensive and easier on the skin for most people
  • Bromine is more effective at high temperatures and pH levels


  • Bromine is more expensive than Chlorine
  • Bromine is very sensitive to sunlight - so if your hot tub is uncovered outdoors, the Bromine will break down very quickly
  1. Sodium Bromide with shock- in this protocol, Sodium Bromide is added to the tub only when you fill it with water, then you just drop in some shock about 15 minutes before you get in the hot tub.  The shock causes the Sodium Bromide to convert to Bromine and sanitize the hot tub.  This process can be done over and over again, and you never need to add more Sodium Bromide, except when you add more water to the hot tub (due to draining or “splash out”).
  • Pros and Cons are the same as with #2, Bromine Tablets

 So, which protocol is right for you?  There are a lot of factors at play, such as:  what you are used to, and what your hot tub manufacturer recommends, etc.  But here are a few thoughts from your friends at pHin:

  1.  Chlorine is best if you:
  • Have an outdoor hot tub with no cover
  • Want a more economical, but still very effective, sanitizer
  1.  Bromine Tabletsare best if you:
  • Have a covered or indoor hot tub that is used relatively frequently (a few times a week)
  • Have a hot tub that changes pH significantly even when not used very frequently
  1. Sodium Bromide with shockis best if you:
  • Have a covered or indoor hot tub that is used relatively infrequently (less than twice a week for example)
  • Have relatively stable pH in your hot tub when you’re not using it (if you have to go out and maintain your pH each week, you might as well drop in some Bromine Tablets too)

 Remember, you need either Chlorine or Bromine - just using shock, or some other system, such as an ionizer or an ozonator alone, will NOT continually sanitize your hot tub.  They will help reduce the amount of Chlorine or Bromine you need, but you’ll still need one of those to keep your hot tub water disinfected and bacteria free.

 And lastly, if you’re looking for a way to remotely monitor your hot tub’s water chemistry, to make sure you always have the right amount of sanitizer (either Chlorine or Bromine), and ensure the proper pH level, pHin monitors all of that, in addition to other chemical levels, and communicates directly with your smartphone to give you alerts when you need to add more chemicals. 

Take the guesswork out of hot tub maintenance, and be confident that your water is always perfectly balanced. 

Learn more at

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