It's been said a thousand times, "Chlorine is for pools, and Bromine is for spas". And that's primarily true, at least it's the conventional wisdom.
However, there are times when Bromine may be the best choice - even for outdoor pools.
Advantages of Bromine over Chlorine?
- Bromine remains effective at higher pH levels than chlorine.
- Bromine is more stable at higher temperatures than chlorine.
- Bromamines retain killing power, chloramines do not.
- Bromamines do not gas off the water surface, as chloramines do.
- Bromine can be reactivated or re-used by adding granular oxidizer (shock).
Advantages of Chlorine over Bromine?
- Chlorine tabs are much cheaper than Bromine, almost half the cost.
- Chlorine can be protected from UV Rays with Stabilizer, Bromine cannot.
- Chlorine is a more powerful oxidizer than Bromine.
- Chlorine is both an oxidizer and a sanitizer, Bromine is only used as a sanitizer.
Can You Shock a Bromine Pool?
You can shock a bromine pool, with non-chlorine shock or with chlorine shock - but you won't need to shock a bromine pool to remove bromamines, (combined bromine), which are still active sanitizers. But you may shock a bromine pool for other reasons, to oxidize contaminants and bacteria or to create bromine. A curious thing about bromine pools, is that shocking reactivates bromide ions to produce - bromine. Adding one or two packets of pool shock regenerates bromine levels, creating essentially free bromine. Chlorine does not share this phenomenon.
Can Bromine be Used in Outdoor Pools?
Yes, bromine tabs can be used in outdoor pools, but the problem with bromine is that it cannot be stabilized or protected from the sun with cyanuric acid. For outdoor pools that receive strong direct sunlight, bromine levels can deplete rapidly, requiring more bromine to maintain healthy levels. Adding CYA to a chlorine pool protects chlorine from strong sunlight, and can double or triple it's staying power, but does not have the same effect on bromine.
Bromine vs. Chlorine for Indoor Pools?
For indoor pools that receive very little sunlight, Bromine is preferred or recommended. The reason for this is that bromamines (compounds of bromine and organics that naturally occur), do not gas-off the surface like chloramines. Chloramines (mono, di and tri) tend to rise to the surface and gas-off, with highest concentrations measured close to the water surface, where swimmers are breathing deeply. Chloramines continue to rise, and strives to continue working, or oxidizing. They are attracted to metal surfaces (ladders, clocks, furniture, duct-work, drop ceilings and steel structural supports. Basically, it can rust out the building, unless the pool chemistry is very carefully managed, and the HVAC systems are built to constantly eject internal air to the outside, while pulling in a constant supply of fresh air.
Bromine vs. Chlorine for Pools with Automatic Covers?
For pools that use an automatic pool cover, Bromine may be a good choice, since the issue of sunlight degradation is largely removed. Bromine and bromamines are also less damaging to auto cover fabrics, as compared to chlorine - all else being equal.
Switching from Chlorine to Bromine?
To switch from chlorine to bromine, one simply needs to stop using chlorine tablets and begin using bromine tablets. If you use a tablet feeder or chlorinator, it should be replaced, so that chlorine residue does not come into contact with bromine, which could be dangerous.
Switching from Bromine to Chlorine?
Going the other way however, requires draining of the pool water, to remove the build-up of bromide ions in the water, which will continue to convert added chlorine into bromine. Even when bromine levels are zero, there still exists a level of bromide ions, which should be removed prior to beginning a chlorine tablet regimen. And, like above - please do not use a brominator for chlorine tablets, replace with a new chlorinator, or use a chlorine floater.
SPP Pool Expert