Sodium Bromide - Please Help!

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J

jdchess

Member
Jun 18, 2023
10
Southeastern NC
Pool Size
10000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-9)
10,000 gallon fiberglass pool. Hayward AquaRite SWG.

Long story short, we had to move out of our house for a few weeks for remediation…long story for another day.

Due to the situation, the pool quickly became an after thought and at some point, the SWG stopped generating. Neighbor mentioned pool had turned green. CYA is at about 60-70 and until cell stopped, FC was staying in the 8-10 range.

I assumed the cell was calcified or had gone bad. I’ve been so covered up with the house and work that there’s no time for anything else so I called a local pool maintenance guy to stop by and check/clean the cell. I wasn’t there, but he pulled the cell and sent me pics. It was heavily calcified. He cleaned it for me and reinstalled it. That was all I intended for him to do but in trying to help out, he also dumped 5lbs of Cal-Hypo shock and 4oz of Regal Yellow Blast which is 99% Sodium Bromide. He was only trying to help but now after reading about the bromine issue, I’m very concerned that he may have created an additional problem that I have to deal with.

He said it was 4oz. Is that enough to cause me to have to drain the pool and refill? What should I do? I would appreciate any help or advice. It’s been a really rough few weeks and I really need some good news on this. I’m hoping that this 4oz didn’t turn it into a bromine pool.

What should I check first and what should i do?
 
Four ounces will give a 10,000 pool a 2.4 ppm bromide bank. That amount could go either way, you'll definitely have bromine in the pool but it might not cause a big enough problem to require correction. The additional sanitizer demand from it might cause your SWG run time to need adjustment, but that's something you'll have to figure out on the fly.

Pool maintenance people at their best: comes to clean a calcified SWG cell and then dumps calcium hypochlorite and bromide in to the water. :rolleyes:

When you are able to I'd concentrate on the SLAM Process to get everything cleared up, and then see how your SWG can keep everything in range going forward. If the chlorine demand is too high you'll want to do a considerable drain to lower the bromide bank. If things seem to be able to hold steady then you got lucky and can just move forward with it.
 
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You can dilute the bromide by adding and removing water at the same time and at the same rate, but I suspect that you will probably not have to do that unless the person added a lot more than 4 oz of sodium bromide.

4 oz is about 3 ppm sodium bromide, which can create 4.7 ppm Br2.
 
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Thank you guys so much for the replies. Couple of questions…

How do you calculate the ppm based on pool size and amount of chem added? Brain not letting me see simple calc…

Also, 10,000 gallons is an estimate. It’s a free form pool. So it may be as little as 9000ish gallons. Obviously, less volume increases ppm in bromine. Is that enough to make a difference in how to proceed? Or is the path forward pretty much the same? Just test and see how FC holds up.
 
(0.250 x 1,000,000)/(10,000 x 8.34) = 2.997.

3 ppm x (79.9/102.9) = ppm bromide.

2.33 ppm bromide.

Each molecule of hypobromite or hypobromous acid contains only one atom of bromine, but it is reported in “equivalents” of Br2.

1 ppm bromide can produce 2 ppm bromine based on how the bromine is reported.

OBr- + HOBr is reported as equivalent to 2Br2.

2 x 2.33 = 4.7 ppm.

4.7/2.25 = 2 ppm chlorine.

So, when you measure your chlorine, about 2 ppm will be bromine and the rest should be chlorine.

You can keep the FC at 10% of CYA + 2 ppm to keep the FC adequate for your pool.

1720797251806.png
 
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You can use the FAS/DPD test to selectively test for bromide in a chlorinated pool sample but you will need glycine tablets to pre treat the sample.

The glycine turns any FC present into CC which is not detected by the DPD but both free and combined bromine is detected by the DPD. The result needs to be multiplied by 2.25 to get the equivalent of bromine from a chlorine kit. At ~2ppm bromine you would need to use the high resolution test and even then you’d only just be at a detectable level. You would be looking for a faint pink and a result of 0.5 - 1ppm.
 

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JamesW said:
(0.250 x 1,000,000)/(10,000 x 8.34) = 2.997.

3 ppm x (79.9/102.9) = ppm bromide.

2.33 ppm bromide.

Each molecule of hypobromite or hypobromous acid contains only one atom of bromine, but it is reported in “equivalents” of Br2.

1 ppm bromide can produce 2 ppm bromine based on how the bromine is reported.

OBr- + HOBr is reported as equivalent to 2Br2.

2 x 2.33 = 4.7 ppm.

4.7/2.25 = 2 ppm chlorine.

So, when you measure your chlorine, about 2 ppm will be bromine and the rest should be chlorine.

You can keep the FC at 10% of CYA + 2 ppm to keep the FC adequate for your pool.

View attachment 595347
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JamesW,

Thank you for the math lesson. Much appreciated. The pool is in full sun and I’m constantly having to refill due to evaporation. When I refill/top-off, be it for evaporation, backwashing, vacuum to waste, or whatever the reason, I’m technically diluting the bromide/bromine, correct? Does it dilute over time like other chems or is a full drain and refill the only way to get rid of it? I read something about it off-gassing over time as well. Any truth to that? Thanks again for the detailed calc for the ppm.
 
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JamesW said:
Evaporation only takes pure water and not dissolved solids.

Can the SWG keep up with the chlorine demand?
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Yes. I believe it can. I haven’t been able to sufficiently test yet. Will hopefully be able to start SLAM this weekend.

So evaporation isn’t removing anything except pure water but is any water that I drain directly through backwashing or waste is in fact diluting the bromide/bromine when I refill?
 
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