Bromine in my SWG pool?

[Rachel B]

Hi- I searched for this but didn’t see an answer. After 4 months ago taking over care of my SWG pool from my pool service, I’m trying to learn all I can.

Pool/attached spa/hot tub is ~7-8yo. Installed by prior owner and was a chlorine (I’m assuming- it definitely wasn’t a SWG) pool. When I purchased 3ya, I had all new equipment installed- including changing over to SWG. Didn’t then, or since, drain + refill the pool.

I read that if there was bromine added to the pool prior to, or if my former pool guys added some algaecides (zero idea if they did or not), that the existing bromine will convert the SWG generated chlorine also to bromine. Is that the case, or did I misinterpret what I read?

I have the Taylor K-2006C FAS-DPD kit w an additional NaCl test kit and then also purchased the smaller bottle kit that is only Chlorine/Bromine (DPD) +pH/TA (accidentally purchased thinking it was a borates test kit- why I have it along w the Big Mac-Daddy kit)

I use the FAS-DPD testing almost daily for my FC/CC/TC testing to keep that level where it should be. So the chlorine levels are good.

My thought is, however, if there is bromine in my pool water, constantly converting the generated chlorine to bromine- assuming that is making my SWG cell work way harder than it should have to.

Question is:
Is there a way to use the “little” test kit in conjunction to tell if there has been added bromine in my pool?

If so, and there is, does that really matter? Would it eventually just go away on its own or would that be something I’d need to do something about?

And I totally could be way off base on this whole line of thinking- know you all will know the answers! I’ve learned so much here in the last few months- Thank you!!!

Rachel

PS- I think I linked my premium pool math account/testing to here… but in case it isn’t- and makes a difference- all testing results just now:

(And, on a side note- the markings on all my test kits are off a bit from what they actually are- I’m a nurse and brought home clean 10cc and a 60cc luer lock syringes- easy to pull apart and rinse then stick my arm in to fill- carry to the shade to test… all markings are actually slightly less than that actual volume- 10ccs measured reaches the 11.5cc line, etc- but I digress- just what I have found on all the included containers and vials… )

pH- 7.8 (going to add the recommended MAcid to take down to 7.6- have waterfall and spa spillover while pump runs that also pushes pH up so have been taking it down to 7.6 and adding MA when it gets to 7.8)
FAS-DPD (25mL sample) FC 6.6
CC 0 (TC 6.6)
CYA 70
CH 450
TA 75

NaCl 3600

With “little” 6-way Residential Test Kit-

Max reading of Cl/Br side is 5/10 so w my known FC 5 I mixed half pool and half tap water = reading in the 3/6 panel (*2)=
DPD Cl 6 & Bromine 12
(Know CC is zero but did the 5gtts of R-0003 TC test- just to see & color unchanged as expected)

pH color right in the middle of the 7.5 and 7.8 indicators- 7.65 but I’ll trust my 44mL “big kit” testing (7.8) over this one w a <6mL sample

TA 80

If you’ve made it this far? You rock! I really appreciate you!!! Xoxo

 

[needsajet]

TBMK... The FC will not convert to BR due to possible past use of BR, but I'm going to link a couple experts just to make sure you get an answer. You definitely have a good handle on everything else so far!

@JamesW @JoyfulNoise

read that if there was bromine added to the pool prior to, or if my former pool guys added some algaecides (zero idea if they did or not), that the existing bromine will convert the SWG generated chlorine also to bromine. Is that the case, or did I misinterpret what I read?

if there is bromine in my pool water, constantly converting the generated chlorine to bromine- assuming that is making my SWG cell work way harder than it should have to.

 

[JoyfulNoise]

Chlorine doesn’t change into bromine … transmutation of chemical elements requires a gigantic nuclear power source or high energy particle accelerator capable of initiating atomic fusion … I’m pretty sure the pool industry hasn’t gone there yet … maybe in a few years

What an SWG DOES DO is it creates active chlorine (a chlorine atom in a +1 oxidation state). If there is any bromide ion (Br-) in the water then the active chlorine will accept electrons from the bromide ion and the bromide will be oxidized to bromine. The chlorine gets reduced back to chloride (Cl-). So, in a round about way using chlorine as the intermediary, the SWG will create both sanitizing chlorine and sanitizing bromine IF the bromine is already in the water.

What makes you think your SWG is creating bromine? Why do you believe it is “working harder than it should”?

 

[Mdragger88]

Which swcg do you have?
Full sig says ppc1 and little sig says ppc2
Ppc1 has the ability to create 15ppm in your pool in 24 hrs
Ppc2 has the ability to create 13ppm in your pool in 24hrs.
How long do you run it & what %?

 

[Rachel B]

Chlorine doesn’t change into bromine … transmutation of chemical elements requires a gigantic nuclear power source or high energy particle accelerator capable of initiating atomic fusion … I’m pretty sure the pool industry hasn’t gone there yet … maybe in a few years

What an SWG DOES DO is it creates active chlorine (a chlorine atom in a +1 oxidation state). If there is any bromide ion (Br-) in the water then the active chlorine will accept electrons from the bromide ion and the bromide will be oxidized to bromine. The chlorine gets reduced back to chloride (Cl-). So, in a round about way using chlorine as the intermediary, the SWG will create both sanitizing chlorine and sanitizing bromine IF the bromine is already in the water.

What makes you think your SWG is creating bromine? Why do you believe it is “working harder than it should”?

Hi thank you so much for the detailed answer (chemistry class was a loooong time ago for me!)

No, I know the SWG is only making chlorine- not actually “making” bromine. I just have no idea if the prior owners/their pool service, w their not SWG pool+spa set up added bromine either directly, or indirectly via algecides. Or, if my former pool guys maybe added bromine containing algecides.

My conjecture was *if* they did, *if* it was still present, and *if* it was breaking down the FC generated by my SWG- *then* the SWG would be running as it is now… versus if the FC wasn’t being broken down, then I could run my SWG at a lesser % and still maintain my current/ideal FC levels.

 

[Rachel B]

Which swcg do you have?
Full sig says ppc1 and little sig says ppc2
Ppc1 has the ability to create 15ppm in your pool in 24 hrs
Ppc2 has the ability to create 13ppm in your pool in 24hrs.
How long do you run it & what %?

Hi I double checked my files and it is a PPC1… need to go adjust my little sig to that It’s at 60% and kinda depends on the day… but is generally ~8 hours. I’d taken it off it’s “schedule” and have been testing out instead of 8a-4p, doing 4 hours am+4 hours pm… last week got my first pool robot vacuum - instructions said to run w pool off so would turn it off to run “Sven”- and push him off the deep end drain covers- and flip him back over- but that’s a different issue

 

[JoyfulNoise]

A properly chlorinated swimming pool that is clean and free of any algae should only lose somewhere between 2-4ppm per daylight hours (depends on the time of year). At the blue-hour and after sundown, the overnight chlorine loss should be zero or very nearly zero IF the pool water is properly balanced and clean.

So one of the first things you should do if you suspect something is eating up the FC is to do an overnight chlorine loss test. You can leave the pump running at night if you wish but the SWG needs to be turned off. Measure the FC at sundown and again before sunrise. The difference should be A LOT less than 1ppm and, in a perfect world, it should really be zero. If it's at 1ppm or over 1ppm FC loss, then something biological is growing.

During the day, you could try adding all of your FC needed in the morning using liquid chlorine and then do a couple of measurements throughout the day. You really shouldn't lose more than 4ppm and, if you are losing a lot more than 4, then there COULD be a chemical issue like bromine.

There's really no definitive test for bromine in water unless you sent a sample to a testing laboratory and paid money for a full analysis. That might be worth it to you if it brings you peace of mind but it's not really worth the expense in my opinion. Even if there were a small amount of bromine in the water, it will eventually all be oxidized to bromates (BrO₃^_ ) by the SWG and your annual rainfall should be sufficient to flush it out of the pool through water exchange. The best way to do a water exchange is to drain the pool down a few inches (don't go below the skimmer inlet, and then let the rain fill it up.

 

[Mdragger88]

Here’s approximately what 60% for 8 hrs looks like in your pool

This is totally normal consumption for this time of year in Florida. Some people experience up to 5ppm/day loss in the heat of summer.
I don’t think you have a lurking bromine problem that’s consuming your fc.
As mentioned above if you’re ever in doubt about something organic do an
Overnight Chlorine Loss Test

 

[Rachel B]

Thank you so much for all of your info! My Overnight FC loss testing came out exactly the same PM after sunset to wee hours of the next morning… so think I’m good! (Also think I’m overthinking things! Haha) thanks again!! Xoxo- Rachel

 

[Rachel B]

Chlorine doesn’t change into bromine … transmutation of chemical elements requires a gigantic nuclear power source or high energy particle accelerator capable of initiating atomic fusion … I’m pretty sure the pool industry hasn’t gone there yet … maybe in a few years

What an SWG DOES DO is it creates active chlorine (a chlorine atom in a +1 oxidation state). If there is any bromide ion (Br-) in the water then the active chlorine will accept electrons from the bromide ion and the bromide will be oxidized to bromine. The chlorine gets reduced back to chloride (Cl-). So, in a round about way using chlorine as the intermediary, the SWG will create both sanitizing chlorine and sanitizing bromine IF the bromine is already in the water.

What makes you think your SWG is creating bromine? Why do you believe it is “working harder than it should”?

Thought I had put, when I first read this… but guess my brain was digesting all the info… but wanted to say I literally lol-ed at your atomic fusion- particle accelerator comment… Quite the imagery of *that* pool’s set up! Haha