SWG, bromine, and shock

notaNative

New member
Apr 23, 2020
3
Michigan/USA
I'm thinking of trying to run bromine sanitizer using my SmarterSpa SWG with 1500ppm NaCl + 50ppm NaBr. I expect that the SWG in this setup will primarily produce chlorine, which will quickly react with bromide ions to produce HOBr, the intended active species. I didn't see any posts describing this setup exactly, and the SmarterSpa manual says that if you want to run a bromine system you should use NaBr for the entire salt profile. That would be expensive and doesn't make sense based on my understanding of how bromine systems work by using a "bromine bank" from NaBr along with chlorine-releasing tablets that activate the bromine. Am I on the right track?

Another related question. Folks talk about how MPS will activate bromide from a bromine bank into HOBr, and will raise free bromine levels significantly. Is there a parallel chloride-to-chlorine activation in SW tubs? I've never checked FC levels after an MPS shock in my NaCl setup, but maybe I should.

We generally use the tub a couple times a week, and I notice that the SWG will cycle several extra times over the following 36hrs (normal baseline is 1-2hrs/day). Once I see its cycle rate come back down, I assume the majority of the organics have been oxidized and it's able to hold a FC level again. So it seems like I could skip adding shock after use as long as the SWG completes this burn-off cycle between uses. Does that sound right?

Thanks!
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,964
Tucson, AZ
Chloride ion can not be oxidized into chlorine by MPS not any other oxidizers. It can only be generated using an electrochemical cell.

You are correct, you should use the SWG cell to produce chlorine and that will activate the bromine in your tub.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
13,485
Evans, Georgia
I assume the majority of the organics have been oxidized and it's able to hold a FC level again. So it seems like I could skip adding shock after use as long as the SWG completes this burn-off cycle between uses. Does that sound right?
I would assume nothing and instead use testing instead to confirm my levels.

Maddie :flower: