Pool Chemicals: Chlorine vs. Bromine

gloved hand holding pool chemicals by water

Chlorine and bromine, used as pool chemicals, are both halogen gases. Each forms a mild acid solution that can disinfect, killing bacteria and algae in pool water. Chlorine and bromine also work well in indoor pools, where algae do not usually develop.

Advantages of Chlorine Treatments

Each individual treatment of chlorine for pools costs less than the same volume of bromine.

Chlorine dissolves quickly in water below 75 degrees F (22 C).

Chlorine treatments are easy to apply and take effect quickly. Add chlorine as a powder or tablets to pool water, using floater pods or a pump.

Disadvantages of Chlorine Treatments

Chlorine is not as stable in water above 75 degrees F as bromine, so that treatment and shocking may need to be done more often. This may negate the cost saving of using chlorine. Chlorine forms other compounds called chloramines, which make the pool more alkaline over a few weeks, and reduce the sanitizing ability of the chlorine.

As the active ingredient in chlorine bleach, chlorine is a well-known skin and eye irritant. It will also fade swimwear and can weaken such elastic ingredients as lycra and spandex. Chlorine also can undo the effects of chemical hair color and permanent wave treatments.

Chlorine has a strong odor that makes it unattractive for many people to swim in and have on their skin, in their eyes, and hair.

Chlorine's effectiveness is reduced by exposure to the UV rays in sunlight.

Solutions for Swimmers in Chlorinated Pools

Swimmers can wear eye protection while swimming, shower and shampoo their hair immediately after swimming, and wash their swimwear with mild soap either in the pool change room or as soon as they get home. They can also wear a pool cap when swimming.

Pool owners must stringently apply pool sanitizing procedures, especially regular pool shock treatments. Most issues with chlorinated water occur in large public pools, not backyard ones.

Advantages of Bromine Treatments

Bromine has been used for years to disinfect spa pools, whirlpools, and hot tubs because it remains more stable in hot water than chlorine. While pre-treatment costs for tablets and shock formulas are higher than chlorine, bromine can be used less often, resulting in a net cost saving.

There are fewer instances of skin, eye or hair problems when swimming in bromine-treated water. Bromine appears to cause no harm to any swimwear fabric.

Bromine has no perceptible taste or smell to the average person and does not lose its disinfecting capabilities, even when it forms bromamine compounds.

Bromamines, unlike chloramines, are effective at killing bacteria and viruses.

Bromine does not lose effectiveness when exposed to UV light.

Disadvantages of Bromine Treatments

Bromine pool treatments are more complex than chlorine, as bromine takes longer to dissolve and mix well with the pool water.

The initial costs are higher but will be recouped over time with a lower number of annual treatments.