Problems with Bromine Pool

[JamesW]

The main problem is that the high dmh is probably locking up most of the bromine and leaving an insufficient amount of hypobromous acid available to work as a sanitizer and oxidizer. Maybe if you had a high enough bromine level, you could manage but how much is enough and how much is too much? Without knowing the dmh level or the equilibrium constants, you're just guessing and that's not safe.

Insufficient sanitizer will create a risk for infectious organisms to spread. Too much and you're creating a hazardous condition.

In my opinion, the pool should be drained and refilled or closed to swimmers.

I know that it's not the answer you or your customer wants to hear, but sometimes you have to do what needs to be done.

 

[TreeFiter]

Oxidizers convert bromide to bromine but at different rates. Chlorine is the fastest, ozone is next, and MPS the slowest, but "slowest" still gets used up in hours unless the bromide bank is very low (which it isn't in this case). So for practical purposes using MPS isn't going to help and is more expensive at converting bromide to bromine than adding chlorine.

When you added chlorine at higher levels, it would oxidize chemicals that bromine doesn't handle as well and is probably why you had chloramine smell. Note that MPS does not handle ammonia or inorganic chloramines well and I suspect does not handle inorganic bromamines well either. MPS will oxidize some chemicals that chlorine doesn't do as well and they overlap for some other chemicals so using MPS can reduce but not eliminate chloramine formation when chlorine is used. I don't know how well it would do in a bromine situation, but given that the MPS gets used up due to the bromide bank it's not something where you can maintain a residual of it.

MPS use in indoor pools is for chlorine pools. In that situation there is an MPS residual that helps to oxidize some chemicals thereby reducing some chloramine formation. That principle would not work well in a bromine pool since the MPS would get used up too quickly oxidizing bromide to bromine.

If you can't get the DMH level down through dilution then the other way to keep the water clear is through better coagulation but that can be tricky to do correctly. For commercial/public pools, SeaKlear PRS Stage 1 and 2 is used while for residential pools it's more dicey but GLB® Clear Blue® as shown in this MSDS is PolyDADMAC so a polymeric cationic (positively charged) clarifier (BioGuard® Polysheen Blue is similar). We don't recommend use of these because they are normally not necessary and are tricky to dose and use correctly, but in your situation you may not have a choice without diluting the DMH from the water.

Shouldn't it be possible to add enough oxidizer to convert all Bromide to Bromine? At that point wouldn't adding more MPS result in a residual? If the pool is free of algae and Bromine levels are sufficient to prevent the growth of bacteria, there shouldn't be much load on the pool. Keep in mind this is an indoor pool with a power cover (not sure I mentioned the cover earlier), so other than bather load (which isn't much as this is a weekend house), there shouldn't be much Bromine demand between visits. When you say "MPS gets used up due to the bromide bank", shouldn't there be a point at which all Bromide has been converted, and consumption of MPS will essentially stop? Should a load be introduced (lets say a swimmer) MPS will again be consumed as Bromine is used up addressing that load.

I'm not suggesting this will work in the current condition, but I'm thinking more about how to manage this pool once some of the water is replaced.

I'm also not super concerned about the added expense of MPS. Normally I would try to save my customers money if possible, but when the customer does everything possible to make the situation more difficult, I have no problem with letting them pay for it. They were very clear that they didn't want chlorine in their pool, which is why we have the problem in the first place.

In terms of what the MPS does or doesn't oxidize, doesn't the Bromine handle essentially the same things Chlorine would? If enough MPS is kept in the pool, there should be plenty of Bromine to handle the brunt of oxidizing duties.

I don't think using clarifiers or coagulants is going to work either. They might keep it clear, but they aren't going to prevent bacterial or viral growth are they?

- - - Updated - - -

The main problem is that the high dmh is probably locking up most of the bromine and leaving an insufficient amount of hypobromous acid available to work as a sanitizer and oxidizer. Maybe if you had a high enough bromine level, you could manage but how much is enough and how much is too much? Without knowing the dmh level or the equilibrium constants, you're just guessing and that's not safe.

Insufficient sanitizer will create a risk for infectious organisms to spread. Too much and you're creating a hazardous condition.

In my opinion, the pool should be drained and refilled or closed to swimmers.

I know that it's not the answer you or your customer wants to hear, but sometimes you have to do what needs to be done.

I'm in agreement with you on this. Unfortunately, the customer ultimately makes that call, and if their track record tells me anything, they will make the wrong call. It really drives me nuts to see people spend half a million dollars on a house with a pool, but refuse to spend any money to maintain it properly. If you can't afford to maintain a pool, you probably shouldn't get one.

 

[chem geek]

Yes, if you add enough oxidizer then you can convert nearly all the bromide to bromine (it slows down with less bromide, but it's mostly all converted in a reasonable time). However, that bromine when used/consumed becomes bromide again so if you are thinking of this being a way of getting rid of bromine, it isn't. Given what you said about how much bromine has cumulatively been added to the pool, I seriously doubt you would convert it all to bromine since it would be an extremely high bromine level. And again, when used/consumed you'd end up with that bromide again.

Bromine does not oxidize as well as chlorine. This is partly why bromine pools or spas are more difficult to keep clear and why they need occasional chlorine or MPS to try and keep clear.

Clarifiers won't help to prevent bacteria or kill viruses, but these are generally easier to kill than algae. It's true that if the DMH is very high then you may need a higher bromine level to be reasonably disinfected, but we don't know the equilibrium constants for that so would just be guessing as to what bromine level is really needed.

 

[JamesW]

Maybe this is one you should walk away from. If you can't do what's necessary to make the pool safe, then it's not worth dealing with.

Note: I think that you're missing the point about the bromine level and dmh. Without being able to calculate the actual level of HOBr in the water, you don't know if it's enough or way too much. What target bromine level are looking to maintain 5 ppm, 20, 50 100 ppm?

 

[TreeFiter]

Yes, if you add enough oxidizer then you can convert nearly all the bromide to bromine (it slows down with less bromide, but it's mostly all converted in a reasonable time). However, that bromine when used/consumed becomes bromide again so if you are thinking of this being a way of getting rid of bromine, it isn't. Given what you said about how much bromine has cumulatively been added to the pool, I seriously doubt you would convert it all to bromine since it would be an extremely high bromine level. And again, when used/consumed you'd end up with that bromide again.

Bromine does not oxidize as well as chlorine. This is partly why bromine pools or spas are more difficult to keep clear and why they need occasional chlorine or MPS to try and keep clear.

Clarifiers won't help to prevent bacteria or kill viruses, but these are generally easier to kill than algae. It's true that if the DMH is very high then you may need a higher bromine level to be reasonably disinfected, but we don't know the equilibrium constants for that so would just be guessing as to what bromine level is really needed.

Thanks chem geek. I'm not expecting Oxy Shock to save me with this pool. I just want to understand the process better, and hopefully be able to use it to keep things going if I can get the customer to replace the water.

 

[TreeFiter]

Maybe this is one you should walk away from. If you can't do what's necessary to make the pool safe, then it's not worth dealing with.

Note: I think that you're missing the point about the bromine level and dmh. Without being able to calculate the actual level of HOBr in the water, you don't know if it's enough or way too much. What target bromine level are looking to maintain 5 ppm, 20, 50 100 ppm?

I don't think I'm missing the point. I get that this pool is pretty much screwed unless they replace a significant amount of water.

If they replace the water, I can add enough Bromine to get 3-5 ppm. Then if I keep an abundance of MPS in the pool, that Bromine level should pretty much stay up towards 3-5 ppm all the time. I would have to replenish MPS on a regular basis, but it would allow for an affordable maintenance program rather than require daily visits.

The key is still that they need to replace the water (or at least most of it).

Unfortunately, the decision to walk away is not mine to make. If it were, I would have walked away the last time there was a problem, and the customer refused to hear what I had to say. They were very disrespectful, and acted as if they were better than me. It would have been my pleasure to leave them to find someone else that even remotely knows what they are doing. Lets face it, the average pool guy is clueless. I was lucky enough to find TFP, where I have learned a lot.

 

[JasonLion]

I was lucky enough to find TFP, where I have learned a lot.

 

[JamesW]

MPS is not necessary. As long as you have enough bromide in the water, using sodium hypochlorite will create bromine. After a drain and refill, you could just add sodium bromide and then only use liquid chlorine (bleach) to maintain the bromine level.

Avoiding the bromine tabs will prevent the buildup of dmh.

Just adding a bunch of mps would not maintain the bromine at the correct level, the mps would all get used up and the bromine level would get very high.

I think that in any case, there needs to be a way to have chlorine added on a regular schedule. Perhaps every third day at most. Continuous additions would be best. A SWG or peristaltic pump might be a good choice.

If possible, it might be better if you could switch them to chlorine.

 

[JasonLion]

JamesW, I think you are missing part of TreeFiter's plan/question. Compare what happens in a pool when all of the bromide is already converted to bromine and then you add a substantial amount of either additional chlorine, or additional MPS. Adding additional chlorine I understand. Without CYA chlorine will cause issues for swimsuits fairly quickly. With CYA you can have a fairly substantial chlorine level without issues, which will reactivate the bromide as the bromine gets used up. If instead you add a substantial amount of MPS, what happens? MPS should not pose a risk for swimsuits (or people), but does it dissipate on it's own, or does it hang around? If it hangs around, it will also reactivate the bromide as the bromine gets used up. This is an indoor pool and we are also assuming that the DMH issue is resolved.

 

[JamesW]

To have the ability to limit the amount of bromine possible, you would have to carefully control the amount of bromide. For every 1 ppm bromide (measured as Br⁺), you would get 2 ppm bromine (measured as Br₂). For example, if you wanted to keep the bromine level in the 1 to 10 pm range, you would need to keep the bromide level between 0.5 and 5.0 ppm.

Adding an initial amount might work because you know that you're starting with zero and you could control how much you add. But then the bromide level would drift down over time and need to be replaced. Without being able to measure bromide levels, it would be difficult to maintain the correct amount of bromide.

Perhaps one could determine the amount of bromide to add based on how much bromine is created when the mps is added. If added mps does not create the target bromine level, one could add more bromide.

I'm not sure how much mps can be added at one time. I don't think that I would exceed the label instructions. I'm not sure what issues, if any, could happen. Persulfate buildup might be an issue if people were sensitive to that.

 

[TreeFiter]

To have the ability to limit the amount of bromine possible, you would have to carefully control the amount of bromide. For every 1 ppm bromide (measured as Br⁺), you would get 2 ppm bromine (measured as Br₂). For example, if you wanted to keep the bromine level in the 1 to 10 pm range, you would need to keep the bromide level between 0.5 and 5.0 ppm.

Adding an initial amount might work because you know that you're starting with zero and you could control how much you add. But then the bromide level would drift down over time and need to be replaced. Without being able to measure bromide levels, it would be difficult to maintain the correct amount of bromide.

Perhaps one could determine the amount of bromide to add based on how much bromine is created when the mps is added. If added mps does not create the target bromine level, one could add more bromide.

I'm not sure how much mps can be added at one time. I don't think that I would exceed the label instructions. I'm not sure what issues, if any, could happen. Persulfate buildup might be an issue if people were sensitive to that.

Sounds like you are getting what I'm saying now. I do have concerns about too much MPS, and how long it will stick around to oxidize the Bromide to Bromine. Its still not an ideal situation, but I think it might be workable. It will most likely require at the minimum weekly visits, where as they are only being serviced every other week, and still complaining that it is too expensive.

I'd like to see them convert to a SWG. My boss has suggested it to them, but I'm not optimistic that they are going to go for it, especially when it would require the additional cost and risk of replacing the water.

 

[TreeFiter]

Thinking about the idea of how long MPS will stick around, it occurred to me that it might not matter all that much. Correct me if I'm wrong here, but if the pool is kept clean and balanced, the Bromine demand should be very low, especially with an opaque cover. This is the principle behind the OCLT, but with Bromine instead of Chlorine. So during the week, while nobody is using the pool, and the cover is on, the Bromine level shouldn't drop much. So as long as I add enough MPS to oxidize all Bromide to Bromine, there should be enough Bromine to maintain for a week as long as the pool isn't being used.

 

[JamesW]

With a low bromine demand, it's possible that you could dose one time per week. In that case, you could use bleach just as easily.

 

[chem geek]

Again, you won't be oxidizing all bromide to bromine. There is likely way more bromide in the pool (given how much bromine has been cumulatively added) so you wouldn't want to convert it all to bromine since the bromine level would be way too high. What you want to do is add chlorine or MPS to create enough bromine to last until your next visit. Since this is an indoor low bather-load pool, the bromine usage should be relatively low so it should not be hard to get the level up and have it last. As for how high you need to go to have it last, you have to experiment. Is 5 ppm TB enough or 10? I don't know.

If there were no bromide left to convert to bromine, then the MPS would last around a week or so if there was little or no bather load, but that isn't your situation since there should be plenty of bromide for the MPS to react with to produce bromine.

 

[TreeFiter]

Again, you won't be oxidizing all bromide to bromine. There is likely way more bromide in the pool (given how much bromine has been cumulatively added) so you wouldn't want to convert it all to bromine since the bromine level would be way too high. What you want to do is add chlorine or MPS to create enough bromine to last until your next visit. Since this is an indoor low bather-load pool, the bromine usage should be relatively low so it should not be hard to get the level up and have it last. As for how high you need to go to have it last, you have to experiment. Is 5 ppm TB enough or 10? I don't know.

If there were no bromide left to convert to bromine, then the MPS would last around a week or so if there was little or no bather load, but that isn't your situation since there should be plenty of bromide for the MPS to react with to produce bromine.

Right. I was referring to after a drain and fill.

In the current condition, there is so much Bromide present that converting it all would be dangerous. I'm going to push for water replacement. Even if they install a SWG they will need to replace the water.

 

[chem geek]

So after a drain refill, if they still insist on using bromine then by avoiding the use of bromine tabs (or certainly too many of them) and instead make a bromide bank by adding sodium bromide, then you can use an oxidizer such as chlorine to create more bromine. Though you could use MPS to create bromine and hopefully have the MPS oxidize some chemicals that perhaps bromine won't, you could also see how chlorine does for that purpose.