How do I use Bromine in my spa (or pool)?

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chem geek

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Yes, the chlorine (or any strong oxidizer such as non-chlorine shock MPS) you add will convert the bromide to bromine, probably sooner than an hour. Your numbers are OK but your CH is higher than it needs to be to prevent foaming. Usually 120-150 ppm is sufficient for that. If the CH gets too high, you can get scaling, though your OK right now.
 

GuinnessPhish

Well-known member
Jul 10, 2012
435
Herndon, VA
just tested the water while my wife is in the tub for about 15 minutes.....

FC is showing up as 1.5, so bromine would be 3.375...


Should I add some bleach while we're still in the tub, or wait until after? What FC level should I be shooting for when I add bleach?
 

chem geek

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Unless you are swimming with strangers with whom you are concerned to get disease from person-to-person transmission, I'd just add an oxidizer (such as bleach) after the soak to handle the bather waste. You add enough so that you start your next soak with around 2 ppm FC. If you were to add a disinfectant or oxidizer during your soak or before your soak, then you'd likely smell it and not be as pleasant for you.

Even with a sanitizer getting very low to zero during your soak isn't bad since you don't soak for more than one hour and you will blast anything in the spa by adding something right after your soak (and technically some of the sanitizer will become monobromamine in a bromine spa which is still a disinfectant or monochloramine in a chlorine spa which still kills, but more slowly). So having a small starting sanitizer level before your soak is reasonable unless you are treating your spa more like a commercial/public spa where anyone with a disease can be soaking with you.
 

GuinnessPhish

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Jul 10, 2012
435
Herndon, VA
chem geek said:
Yes, with an FC of 1.0 your bromine level is 2.25 ppm.
You can shoot for an FC of around 2 ppm which is a bromine level of 4.5 ppm.
With bromine, you don't test CC since combined bromine shows up as FC so you are really measuring Total Bromine.
TA and CH are still relevant for the saturation index to prevent scaling and pH and TA are relevant for how fast your pH may rise (i.e. you adjust TA to find the sweet spot for pH stability, but note that bromine tabs are net acidic).



So, using bromine tabs will lower pH?

If pH is just below 7.2, what should I do to get pH higher?
 

chem geek

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Bromine tabs will lower the pH if there is no carbon dioxide outgassing. So if your TA is higher or you have more aeration, then you can have pH balance or even the pH rising. So if your pH tends to consistently fall over time, you can raise your TA level (within reason). I wouldn't go much above 120 ppm unless your CH level is low and you don't need it higher to prevent foaming. I'll bet that having a TA in the 80-100 range might be sufficient for better pH stability, but it really depends on the amount of aeration and use of your spa.

For a short term increase in pH, you can add a base such as 20 Mule Team Borax or pH Up (Arm & Hammer Super Washing Soda) where the latter will raise the TA more than the former.

Remember to measure your pH at a consistent point in time, such as just before your soak. The pH and bromine levels vary quite a bit during and after your soak especially after you add an oxidizer to the water. The pH and bromine level will go up after adding an oxidizer and will come back down as your bather waste gets oxidized.
 

GuinnessPhish

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Jul 10, 2012
435
Herndon, VA
I just added about 3 oz of pH up a short while ago.

Planning on soaking for about an hour (half hour X 2 people).


How much 6% bleach should I be adding afterward?

Right after bleach goes in, put the bromine floater back in, let it stay open for 20 minutes or so?
 

chem geek

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GuinnessPhish said:
How much 6% bleach should I be adding afterward?

Right after bleach goes in, put the bromine floater back in, let it stay open for 20 minutes or so?
Every person-hour of soaking needs around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS) to oxidize the bather waste. This assumes a hot (104ºF) spa and no ozonator and minimal background oxidizer (bromine from the bromine tabs). So you can try 5 fluid ounces and then see what the bromine reading is when you start your next soak. If the bromine level is too high at the start of your next soak, then scale back the amount you add per person-hour.

Yes, keep the cover open for a bit -- 30 minutes would be better but anything to let the oxidized bather waste outgas would be good. Some of the chemicals that outgas not only smell but are more damaging for the cover and most of these are produced in the first hour after adding the oxidizer.
 

chem geek

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The bromine tabs are to provide a background level of bromine in between soaks. If you used the tub every day or two, you wouldn't need the bromine tabs and would instead just reactivate bromide to bromine by adding an oxidizer after your soak where the bromine would last by the time you next soak. Think of bromine tabs as being a convenient way to continuously dose bromine.
 

plwhorse

Member
Nov 15, 2012
6
Had a question about bromine to anyone that can answer it. I switched from chlorine to bromine in my spa about a week ago. I purchased bromine tablets and a floater not realizing that I needed to establish a "reserve". I went to the spa store and told them I needed to establish a bromine reserve in my tub and they handed me some granular bromine. Took it home and then realized that it was not pure sodium bromide but bromide and oxidizer mixed. I used it as per instructions and have got a bromine level of about 3 now. All is good...right? My concern is that with my floater and adding granular also that my bromine levels will continue to rise even with oxidizer in the mix. Is this a correct assumption and if so is it bad to have the bromine level increasing? How would I test for total bromine?
 

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UnderWaterVanya

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plwhorse said:
Had a question about bromine to anyone that can answer it. I switched from chlorine to bromine in my spa about a week ago. I purchased bromine tablets and a floater not realizing that I needed to establish a "reserve". I went to the spa store and told them I needed to establish a bromine reserve in my tub and they handed me some granular bromine. Took it home and then realized that it was not pure sodium bromide but bromide and oxidizer mixed. I used it as per instructions and have got a bromine level of about 3 now. All is good...right? My concern is that with my floater and adding granular also that my bromine levels will continue to rise even with oxidizer in the mix. Is this a correct assumption and if so is it bad to have the bromine level increasing? How would I test for total bromine?
Chem geek mentioned recently that you can add one drop of ammonia to your sample and that will convert the FC to CC and leave the bromine measuring as FC and then you multiply by 2.25 to get the bromine level - I think. I will look for the post.
 

chem geek

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If you keep using tabs or the bromide with oxidizer, the bromide level will increase over time. It's a slow way to increase your bromide bank, but it will happen. Even after a week, you'll probably be mostly a bromine spa and I wouldn't worry about it not being fully bromine right away. The chlorine and bromine test kits do not distinguish between the two -- the FC portion of the tests will test for Free Chlorine or Total Bromine with the only difference being the units of measurement (bromine units are 2.25 times the chlorine units). You can use the bromine tabs in the floater for a background level of bromine and use the bromide+oxidizer for a bromine boost added right after each soak to oxidize bather waste. Once you've built up a bromide bank, you can then just add an oxidizer after your soak and won't need any more bromide (the bromine from the tabs should be more than enough to make up for any bromide lost from bromine outgassing).
 

GuinnessPhish

Well-known member
Jul 10, 2012
435
Herndon, VA
chem geek said:
Bromine tabs will lower the pH if there is no carbon dioxide outgassing. So if your TA is higher or you have more aeration, then you can have pH balance or even the pH rising. So if your pH tends to consistently fall over time, you can raise your TA level (within reason). I wouldn't go much above 120 ppm unless your CH level is low and you don't need it higher to prevent foaming. I'll bet that having a TA in the 80-100 range might be sufficient for better pH stability, but it really depends on the amount of aeration and use of your spa.

For a short term increase in pH, you can add a base such as 20 Mule Team Borax or pH Up (Arm & Hammer Super Washing Soda) where the latter will raise the TA more than the former.

Remember to measure your pH at a consistent point in time, such as just before your soak. The pH and bromine levels vary quite a bit during and after your soak especially after you add an oxidizer to the water. The pH and bromine level will go up after adding an oxidizer and will come back down as your bather waste gets oxidized.


Question regarding TA.

I just added some water to my hot tub because it was getting a little low.

I retested TA and CH: TA is 50, CH is 150.


I added some bleach to bring FC up to 2 (or more accurately, bromine up to 4.5).


Prior to adding the water, my pH seemed to have leveled out at about 7.5, with me adding bleach every other day or so to reactivate bromide.

Is my TA fine for now? or should I try increasing it? or should I just try to see how my pH is holding?
 

chem geek

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Just see how the pH is holding. If it is dropping over time, then increase the TA. If it's stable, just leave it as is. If it's rising over time, also leave it but consider using 50 ppm Borates if you aren't doing so already.
 

yog27

Member
Dec 5, 2012
7
On a previous post you wrote:" If you add sodium bromide to your water and have an ozonator you might be able to achieve the constant bromine level without the floater since the ozone is constantly oxidizing the bromide while it is on. However, you might deplete the bromide reserve quickly this way, leading to a shorter time between drain and refills"

Why drain and refill? Could i just shock or add sodium bromide?
 

chem geek

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Welcome to TFP! :wave:

Yes, you could just add more sodium bromide if it gets lower. It gets lower from a slow outgassing of bromine (and some bromine combining with organics and getting caught in the filter and washed away during cleaning).

It was waterbear that wrote the post with the statement you quoted, not me. Not that I don't make mistakes as well; I do. What he said was accurate, but incomplete since as you point out you can work around the bromide depletion by simply adding more.

Of course, you will need to eventually change the water when the buildup of unoxidized organics becomes intolerable such that the water gets dull/cloudy or smelly or otherwise undesirable (and where chlorine shocking doesn't clear it).
 

yog27

Member
Dec 5, 2012
7
Thank You!

With ozonator can i just shock and add sodium bromide if need once a week?
 

chem geek

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You may still need to add more oxidizer after your soak. It depends on how much you soak and on the power of your ozonator. See if you have a measurable bromine level around 12 hours after your soak and again just before your next soak. If the bromine level is close to zero, then you'll need to manually add some oxidizer after each soak. Usually, ozonators are able to handle about half the usual bather load.
 
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