Added too much Sodium Bromide to a Chlorine pool ...what do I do now?

[ScottF]

I added 3 lbs of Sodium Bromide to my chlorine pool. I was told that Thiosulphate will neutralize bromine. However won't bromine simply be regenerated when I add chlorine and it reacts with the Bromide Salts still in the pool. Does Thiosulphate remove the Bromide Salt? ? How do I resolve this issue without draining the pool. Any help would be greatly appreciated. The pool is NOT holding any chlorine. I was advised to add an inline chlorine feeder to constantly add chlorine to the pool. Is that enough?

[PoolDoc]

You need to read this page:
once-a-bromine-pool-always-a-bromine-pool.html

Sodium bromide apparently can be removed . . . over time, with lots of chlorine. Sodium thiosulphate will have no effect. What will have an effect are large doses of chlorine and time. But, I have no idea how much chlorine or time it will take. I'll email Chem_Geek and see if he's found anything that predicts conversion of bromide to bromate.

Of course, according to the EPA, that much bromate is 'toxic', so that's another issue. I think some of that is typical EPA hype ("will increase your chance of dying from toenail cancer 160 years from now", etc.), but again, I'm not sure.

If you have a United Chemical product, call them. In times past, they actually had some knowledgeable people on the phones. And Jock Hamilton probably would have known how to predict the conversion rate. But he died a few a few years ago, and I don't know what they are like now.

BTW, how many gallons are in your pool? That's an awfully large dose for most residential pools.

Was it a 100% sodium bromide product?

Is draining your pool an option?

Ben

[chem geek]

According to this paper (which I've purchased though it is also visible as section 5 in this link), about 50% of the bromine is converted to bromate after 2 hours of exposure to sunlight with much of the rest converted to bromide. The conditions used were with seawater (which is around 67 mg/L Br2) and at a pH of 8 with around 4.5 ppm chlorine used in the experiment. Lower pH causes the decomposition and disproportionation reactions to occur more quickly, but without sunlight and at diluted concentrations in pools such reactions are slow. This link used de-ionized and raw water and found similar results with sunlight-induced bromate formation of 6.6% to 32% of bromide ion.

So if the amount of bromide added isn't too high, then keeping the pool chlorinated and exposing the water to sunlight should remove the bromide over time, probably in a few days if one uses typical sodium bromide algaecide treatments that are only a few ppm sodium bromide in dosage (but see below becaus your dose is much higher than that). Roughly take 1/4th the rate of chlorine demand and figure that's how much bromide is lost. In theory, the chlorine demand should be higher for a bromine pool since the bromine is unstabilized and the experiments seemed to show it decomposes fairly rapidly in sunlight.

The point about bromine tabs is relevant because the 5,5-dimethylhydantoin (DMH) in bromine tablets acts like CYA in binding to bromine so would slow down its degradation in sunlight.

3 pounds of sodium bromide in 10,000 gallons would be 56 ppm bromine. So this could take quite a while to remove.