The ongoing debate with hot tub sanitation is whether to use chlorine or bromine. I have found in my 20 plus years in the hot tub industry that bromine makes the most sense to use in hot water.
Chlorine is a very effective sanitizer in swimming pool water, but a portable hot tub (one not attached to a pool) is going to have more sanitizer issues like high water temperature and a smaller amount of water per person. Five people in a 300-gallon hot tub contribute as much wastes to the water as 375 people in an average size backyard pool. Wastes in this case would be body oils, sweat, make-up, lotions, etc.
More of these examples are released into hot water than into cold water. All of that waste puts a heavy load on chlorine resulting in chlorine odors and irritation to eyes and skin as a result of a buildup of chloramines in the water. Bromine does not have this problem. When bromine reacts with wastes in the water it does not lose its ability to sanitize, chlorine does. Basically, chlorine reacts with wastes and is dead, leaving behind that chlorine smell and chloramines that can cause skin and eye irritation. Bromine reacts with wastes and turns into bromamines. Bromamines will continue to sanitize after reacting with wastes and will not have an odor left behind or cause skin or eye irritation.
PH is another reason why bromine is a better choice than chlorine for hot tub use. The correct PH range for pools and spas is 7.4 to 7.8. At some time your PH level in your tub will stray from this range. It happens to all of us. If you’re using chlorine in your tub and your PH reaches a level of 8.0 only about 25% of the chlorine in your tub is actively working to sanitize the water. This means that 75% of the total chlorine in your water has turned into chloramines and is doing nothing more than causing that chlorine smell and skin and eye irritation. Bromine on the other hand works effectively throughout the PH scale sanitizing all the way.
Bromine can also be reactivated in the water by using the chemical potassium peroxymonosulfate. This chemical wakes up the bromide salts in the water which have gone dormant and produces bromine that starts sanitizing immediately. When the sanatizing ability of chlorine is gone it’s gone forever.
The best way for you to find more facts on water sanitation is to call or stop by your local hot tub dealer and ask to speak with their techs, not the salespeople. The technicians deal with water chemistry on a daily basis and are your best source of information.