Hot Tub Chemicals: Chlorine vs. Bromine

hot tub

To keep bacteria from growing in the warm water in your hot tub, you should use chemicals like chlorine and bromine. The most commonly used chemical, chlorine, keeps bacteria in pools, too, at safe levels. However, it is used in hot tubs at different concentrations.

In addition, you can use bromine in your hot tub, which does nearly the same thing as chlorine. But, because bromine does not “gas off” at about 98°F, there is less odor in the hot tub when using this chemical.

Whether you use chlorine or bromine is up to you, though you must use one. Check out this brief comparison to decide which is best for your hot tub.

Warning: Contact with any of these chemicals can produce caustic burns and be harmful if you do not take the proper safety precautions. Allows follow the directions on your product and wear safety gear.

Chlorine in Hot Tubs

Chlorine for hot-tub use comes in the form of tablets and granules. Be careful because there is a major difference between chlorine that is used for pools and the kind that is used for hot tubs. Certain chlorine pool tablets have a higher acidic level and/or calcium content that can leave stains on hot tubs or cause excessive odors.

Trichlor is a pool tablet of this nature. It should not be used in hot tubs because of its acidity and its ability to bleach the hot-tub finish. Calcium hypochlorite is another pool tablet that, when used in hot tubs, can leave deposits on the heater parts and fittings.

Sodium Dichlor

Two types of chlorine are recommended for hot-tub use — sodium-dichlor granules and a plug-in salt system. Sodium dichlor is neither too acidic nor alkaline and does not run out with high temperatures. It is specifically designed for hot-tub use, though it should be dissolved first in water and then added to a hot tub.

Salt System

The other option is to install a self-feeding salt system that produces chlorine from salt crystals. The use of saltwater purification of a hot tub works in much the same way as in a pool, requiring no changes to the hot tub.

Bromine in Hot Tubs

Bromine is a popular alternative for hot-tub use because it does not produce the odors that chlorine can. Bromine is added to hot tubs in the form of granules, nuggets, and tablets. The two most common types of bromine sanitizers are sodium bromide and 1-Bromo-3-chloro-5,5-dimethylhydantoin, or BCDMH.

Sodium bromide requires something called an oxidizer, such as chlorine or potassium monopersulfate. BCDMH, on the other hand, is self-activating because it contains some chlorine. Bromine works better in hotter water and decreased water volumes than chlorine, but because it is sensitive to sunlight and can deteriorate, it is not used in pools.

Though bromine costs slightly more than chlorine to sanitize your hot tub, it’s also arguably more effective for hot-tube use and does not have the odor that chlorine does. However, if you’re worried about costs, you can use chlorine instead.