So my neighbour has a hot tub and didn't have any sodium bromide, nor is it possible to buy it in stores in my area. So she used a 2 part bromine solution (it's only like 14% sodium bromide in it and a few other things, I'm guessing to activate the bromide). Plus she's using bromine tabs in a floater. She uses bleach after use and to shock the tub.

Now I know that until enough bromine tabs dissolve that it will be a chlorine tub and not a bromine tub, but would the bromine solution she used change that? Would it make it a bromine tub? If not, how do you tell once enough bromine tabs have dissolved to turn it from a chlorine tub to a bromine one?

She also has something called "bromo shock." It's a granular bromine solution that says it's to be used to shock bromine tubs. Should she use that to shock, or continue to use bleach?

For testing, she does the same thing I do, uses test strips to get a rough idea, and takes a sample into the spa store twice a week to get it properly tested. I know, I know, we need to get a taylor test kit. But they don't sell them in my area, so we have to buy from Amazon or E-bay, but the shipping, taxes and duties are killer.

I would not mix bromine & chlorine together. They tend to cancel each other out. Also, chlorine (or bleach) tends to be too abrasive to the spa surface over a period of time, and will take off the finish. Just stick with bromine tabs and bromine shock. Also, consider a "spa frog" (bromine/mineral floater). This makes it an easier DIY task, with minerals giving great water quality. Good luck.

Chlorine used in the appropriate amount is just fine for a spa and is no more harmful to the finish than any other sanitizer. Mineral floaters are unnecessary and can be problematic over time. This may not be as big an issue with a freestanding spa if you are changing the water on a regular basis, but you do not want to use mineral packs in a spa attached to a pool.