How do you clean your hot tub when you have had this bacteria (folliculitis)in it. It's the middle of winter(-25 C) and I will not be able to fully empty tub. Is there some chemical you can put in the water? I have maintained proper chemical levels. I use bromine instead of chlorine.

Try super chlorination

Can you use that when you use bromine.

Yes you can when shocking it higher the water temp is the quicker it gets gassed off and also the folliculitis tends to love high temp water. So I would lower the temp to 70 then shock it with calcium hypochlorite 3 times the recommended dose and consider switching back to chlorine