Sodium Bromide

Sodium Bromide

If you add 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.

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

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.

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. 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.

Sodium bromide is NOT "banned" in Canada

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.

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. To my understanding, neither ozonation or UV are particularly useful, and certainly not necessary for a bromine spa, so if your tub is so equipped and you'd like to use bromine legally and safely, you could feel free to 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.

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