rising ph

[Danmickread]

Hi.
I seem to have trouble with rising ph in my hot tub.
I have a bromine tub with a floater wich keeps my bromine level around 5 ppm i also have an ozonator. I am hardly using the tub at the min cause weather is rubbish here in UK so the tub isn't getting much airation but no matter what i do the ph seems to keep rising. My Ta is on 85 at the min with ph of 7.6 but i bet u over the next couple of days its back up to 8.0-8.2 without it even being used. My Ta has been even lower than this in the past but still find my self having to keep adding acid to keep ph down. The Ta as well as ph appeared to have increased last time i tested. I thought the bromine tablets were acidic and supposed to have the opposite affect?
The only other chemical im adding is non chlorine shock if my bromine goes low
Any help on this would be appreciated.
Thanks
Dan

 

[JasonLion]

If you lower your TA enough, perhaps around 40, PH will be stable at lower levels. Bromine isn't nearly acidic enough to keep up with the rate at which TA increases PH.

 

[chem geek]

The bromine tabs are net acidic, but I suspect you have that dialed down pretty low because the ozonator is creating most of the bromine for you. The ozone-created bromine raises pH and the usage/consumption of that bromine lowers the pH so the net is neutral. That's why a lower TA level should help since the pH rise is coming from carbon dioxide outgassing -- TA is a measure (among other things) of the over-carbonation of the water.

 

[Danmickread]

Can u disconnect the ozonator then?

 

[chem geek]

I think Jason's suggestion of lowering the TA level is better. Having the ozonator generate bromine for you is nice-to-have and it also oxidizes bather waste if you use the spa a lot.