One answer why people would choose Bromine for a pool, from my personal experience. I am not advocating the use of Bromine in pool, especially now that so much information is available for managing a chlorine pool.
Way, Way, back in the 80's, when we moved into this house, the pool had an in-line chlorine tab feeder, at the pumping station. We moved in early fall, and kept the pool open all fall/winter with good looking water. Next summer, as my dogs started spending more and more time in the pool, even napping, down in the water on steps, I began to see bleaching of their coats. Most were show/working dogs and considered to have some of the best coats. The highlights in the Fawn Mastiff coats began to fade (several different colors of highlights in the outer harsh coat) and bleach out. Rottie coats started to turn from shiny black to dull, reddish black. At the same time DH complained about the chlorine smell and skin irritation.
I knew nothing about all the values and relationships and tested only for pH and Cl. Time for a change.
In 87 we had an in-line Bromine tab feeder installed and CL feeder removed. Doggie coat conditions improved dramatically and DH stopped complaining about the Cl.
It was as simple as that. I did find that the cost, back then, was pretty much the same. The Bromine cost more up front than chlorine tabs but it went further (longer before refilling the feeder). I probably spent about the same on the weekly "shock"
for both "systems" [sic].
Soon after that, don't remember how long, I switched to the commercial sized Nature 2 canister. And continued to use Nature 2, and until last summer
(when I found TFP) Floatron, for three years. Yes, I did get metal stains over the years. I'm still working on copper stains that will probably be gone about the time I have to re-plaster the pool. My current plaster is 14 years old and in great shape considering the abuse it has withstood. 1) I didn't know anything about water balance other than pH and Cl 2) It became scaled so much that in 2004 virtually all the blue plaster was covered with white, stained scale and 3) I did two (maybe) three heavy acid washes between 1996 and 2008. I did an AA treatment fall 2009 that released a lot of stain and have kept adequate sequestrate levels that have continued to keep iron from staining and has been slowly releasing the remaining scale.
BTW.... I never had a hint of algae while using the Nature 2 commercial or the Floatron, as long as water was kept filtering virtually 24/7 most of the year with a little less time in winter, BUT just how safe was my pool really????? It got "shocked" once or twice weekly, BUT?????????????????
gg=alice
Well, here's a thread that might help you. 
