Sodium Bromide - Further Reading

Sodium Bromide

Sodium bromide and the resulting bromine is not recommended for pools but can be useful in spa. A spa is not a small pool and bromine can be a good sanitizer for spas.

If you add sodium bromide to a pool or spa it combines with chlorine to form bromine. Bromine is a disinfectent and when bromine disinfects, it forms bromamines (analagous to chloramine). When any future chlorine product is added, the bromamines reconvert to bromine and the cycle repeats.[1]

UV in sunlight breaks down bromine into bromide salt. Then any oxidizer, including chlorine, will reactivate it (oxidize it) back to bromine.[2]

The bromide to bromine cycle is:

  • Bromide + Chlorine ---> Bromine + Chloride
  • Bromine broken down by sunlight or oxidizing ammonia or an organic ---> Bromide

So you can see from the above cycle, that you don't get rid of bromide/bromine except by its physical removal from the water. This is very different than chlorine which goes to chloride (salt) and stays there.

Sodium Bromide in Pools

Sodium bromide is never a good solution for a home owner maintaining a residential pool. It costs extra, adds complexity, covers up underlying problems, and if not used correctly makes things worse than they were to start with.[3]

Sodium bromide has become popular because so many people have high CYA levels. Sodium bromide can help get some sanitizer into the pool that will be effective even when your CYA level is too high. It is far far better to simply lower the CYA level. If you do that, not only is the current problem solved, but many future problems are also solved.

Sodium bromide can be handy for pool services that only show up once a week as a quick fix that gets around underlying problems. In that context, it does have it's uses. However, the "default" context here, if you don't say otherwise, is the home owner taking care of their own pool. In that context sodium bromide adds complexity and hides the underlying problem of high CYA.

Adding sodium bromide to a chlorine pool essentially turns it into a bromine pool.[4] The idea that the bromine is gone in 24 hours is pretty much without merit. As soon as chlorine is introduced into the pool, it converts it back to active bromine. It takes a long while to get rid of all the bromine from even just one treatment. Bromine based algaecides are not recommended either for the same reason.

Research the ingredients in algaecides to treat mustard algae. Some of them contain sodium bromide as the primary active ingredient such as:

  • No Mor Problems is a sodium bromide based preventative algaecide. It contains approx. 41% sodium bromide, the rest being "inert".[5]
  • Aquabrite Yellow Quell is sodium bromide
  • ClearView Yellow Aid Sodium Bromide Algaecide
  • Jacks Magic - The Yellow Stuff algaecide - 99% sodium bromide

Sodium Bromide in Spas

Read How do I use Bromine in my spa (or pool)?

Testing for Bromide and Bromine

There is no easy way to measure bromide levels or any need to do so. Once you add the initial amount of sodium bromide, the reserve stays in the water. Any oxidizer - ozone, chlorine or MPS - will convert some of the bromide into bromine.[6]

The standard test kits that test for chloride also react with bromide and there is always so much chloride in the water that it will swamp any bromide result anyway.[7]

As for bromine, the tests are for halogen where bromine and chlorine will both react whether it is an OTO, DPD or FAS-DPD test. The only difference is that technically bromine is 2.25 times heavier than chlorine which is why the test kits have dual scales with bromine twice as high as chlorine.

You can use any chlorine test kit to check bromine, BUT keep in mind that Combined Bromine will measure a Free Chlorine (FC). There is no distinction between Free Bromine and Combined Bromine (at least when the combined bromine is bromine combined with ammonia -- monobromamine). So bromine test kits just report this as Total Bromine and there is no need for an R-0003 reagent. Note that unlike combined chlorine, combined bromine is still a disinfectant so isn't of concern, though it can smell different than bromine.[8][9]

Bromine units are 2.25 times higher than chlorine so multiply any FC reading by 2.25 to get Total Bromine.

If you measure a zero bromine reading, that just means there is no bromine or chlorine, but it does not mean there is no bromide. Any chlorine that is then added to the water would then reactivate the bromide to bromine and would show up in your test kit as if you had chlorine, but it's really bromine because the test kit does not know the difference.

Sodium Bromide is NOT "banned" in Canada

TL;DR- Sodium bromide is still legal and safe to use in Canada without MPS, ozonation, and UV; it's just harder to find.

It's commonly repeated that sodium bromide has been banned in Canada, that Health Canada considers bromine to be unsafe for hot tubs, and other such things. While it is true that certain sodium bromide products have been found to have health risks, and banned for sale by regulations from Health Canada, the truth is that sodium bromide is still legal, and found to be safe by Health Canada for other uses including the main "waterbear" bromine method found in this forum.[10]

The following sodium bromide products/applications have been banned by Health Canada:

  • sodium bromide spa products used in combination with potassium monopersulfate (MPS)
  • sodium bromide swimming pool and spa products used in combination with electrolysis, ozonation or UV

That's it. If you are using sodium bromide in a spa without using electrolysis (saltwater generator), ozonation, UV, or MPS, then Health Canada has not only deemed use of sodium bromide legal, but safe as well. From Health Canada:

With respect to human health, risks of concern were identified for the use of sodium bromide products used in combination with bromine electrolysis devices and sodium bromide spa sanitizers used in combination with potassium monopersulfate. No risks of concern were identified for all other uses of sodium bromide when used according to the revised label directions. Also when used according to the revised label directions, sodium bromide is not expected to pose risks of concern to the environment.

Liquid chlorine (bleach) is supposed to be better at activating bromide into bromine with fewer dissolved solids (sulphites) anyway, so that's generally not recommended on this forum anyway. Neither ozonation or UV are necessary for a bromine spa, so if your tub is so equipped and you'd like to use bromine legally and safely, you could disable or remove the UV/ozonation equipment.

So why is pure sodium bromide hard to find, then? A guess is that electrolysis and MPS formed the majority of applications for bromine, and these applications are now not permitted. Secondly, a lot of the misinformation and confusion about sodium bromide has led people to thinking that it's not allowed in Canada, and that they shouldn't be buying it, further decreasing the demand for it in stores. Finally, the Health Canada regulations require labeling to the effect that sodium bromide shouldn't be used in combination with electrolysis, ozonation or UV, and that manufacturers and retailers have determined that it isn't worth the hassle to update product labels for the admittedly small market for sodium bromide.

The good news is that since it's legal, it's still possible to find and order sodium bromide, despite it being more difficult to find in stores, and still safe for use as long as you are using it as directed, without MPS, ozonation, or UV.