Bromine question

Does Bromine increase or decrease pH... and what are some common reasons pH goes up? aeration? heat?

Don't know - are you using this in a spa or pool? PH can be raised if the PH is low and you aerate (spa jets) or when plaster is curing.

its for a hottub, not connected to the pool. PH always seems to be high, wondering if its because of the bromine or the constant bubbles (aeration)

Bromine is normally about 5 - 6 pH so is on the low side.
Increasing pH will be mostly due to the aeration, make up water quality, and many other additives to your spa (scents, bath oils, sweat, etc).

Thanks, I better stop sweating in the hot tub