SWCG with bromine?

[DrNinjaman]

After reading through the Bromine and You sticky, I was wondering about the utility of using a saltwater chlorine generator with bromine. Since bromine requires regular oxidization to maintain sanitizer levels, and chlorine provides that, would using bromine with a SWCG result in a system that did not have to run as frequently to maintain the sanitizer, working much like an ozone generator, and replacing the bromine floatie? Bromine then being more stable at high temperatures wouldn't require the chlorine generator to run as much as it would if you were relying on the chlorine alone to provide sanitation? Am I over-complicating this? I mean, fundamentally, bromine is an enhancement of chlorine sanitation that's chosen because it is more stable and doesn't get consumed as readily as chlorine on its own, right? It's also more effective at higher pH, making it safer, especially for smaller vessels which would experience larger pH swings. I have a Controlmatic Chlormaker system, and it's pretty nice for minimizing necessary maintenance, but I've been having some corrosion issues with the heater, and I'm interested in developing a method that reduces that as much as possible. Hence, my inquiry regarding bromine. Running the salt cell less seems ideal, both for maximizing cell life, and for reducing potential stray currents in the water driving corrosion. This seems feasible to me, anyone have any thoughts? The obvious question to me would be whether this has any advantage over just using a bromine floatie? Doing that doesn't require adding a pile of salt to the water.

 

[wayner]

Are you worried about corrosion due to salt? Aren't Chlorine and Bromine just as corrosive to metal?

I have a Controlmatic SmarterSpa - I used to use Bromine but now I just use the SWCG. Is your goal to save money in not having to replace the SWCG as often?

 

[DrNinjaman]

Are you worried about corrosion due to salt? Aren't Chlorine and Bromine just as corrosive to metal?

I have a Controlmatic SmarterSpa - I used to use Bromine but now I just use the SWCG. Is your goal to save money in not having to replace the SWCG as often?

I suppose my objective would be to extend the life of the salt cell and realize the benefits of using bromine with it's greater pH range effectiveness and higher temperature stability. Bromine may be just as corrosive as chlorine, but if the salt cell is pushing an electrical potential into the water, then it would seem that running the cell less frequently might slow the development of corrosion damage. Probably doesn't work so cleanly though. I'm sure corrosion can carry on in the absence of the cell being powered on.

 

[jgofnj]

Am I missing something? I understand you cannot use bromine and chlorine at the same time.it’s one or the other. SWG produces chlorine.

 

[DrNinjaman]

Am I missing something? I understand you cannot use bromine and chlorine at the same time.it’s one or the other. SWG produces chlorine.

If you read the "Bromine in Your Spa" sticky, you would learn that you definitely can use them together. Bromine requires the use of an oxidizer to replenish the hydrobromous acid from the residual "bromide bank" in the water, and chlorine is often used to do this. The chlorine gets rapidly consumed converting the bromine back to an active form. Going back to a chlorine-only spa is far more difficult, apparently.

 

[jgofnj]

If you read the "Bromine in Your Spa" sticky, you would learn that you definitely can use them together. Bromine requires the use of an oxidizer to replenish the hydrobromous acid from the residual "bromide bank" in the water, and chlorine is often used to do this. The chlorine gets rapidly consumed converting the bromine back to an active form. Going back to a chlorine-only spa is far more difficult, apparently.

Did not know that. Learn something new everyday. Thanks.

 

[Jay G]

Am I missing something? I understand you cannot use bromine and chlorine at the same time.it’s one or the other. SWG produces chlorine.

I shock my bromine tub all the time with chlorine.

 

[Jay G]

Going back to a chlorine-only spa is far more difficult, apparently.

Easy as a drain and fill.

 

[gsw234]

After reading through the Bromine and You sticky, I was wondering about the utility of using a saltwater chlorine generator with bromine. Since bromine requires regular oxidization to maintain sanitizer levels, and chlorine provides that, would using bromine with a SWCG result in a system that did not have to run as frequently to maintain the sanitizer, working much like an ozone generator, and replacing the bromine floatie? Bromine then being more stable at high temperatures wouldn't require the chlorine generator to run as much as it would if you were relying on the chlorine alone to provide sanitation? Am I over-complicating this? I mean, fundamentally, bromine is an enhancement of chlorine sanitation that's chosen because it is more stable and doesn't get consumed as readily as chlorine on its own, right? It's also more effective at higher pH, making it safer, especially for smaller vessels which would experience larger pH swings. I have a Controlmatic Chlormaker system, and it's pretty nice for minimizing necessary maintenance, but I've been having some corrosion issues with the heater, and I'm interested in developing a method that reduces that as much as possible. Hence, my inquiry regarding bromine. Running the salt cell less seems ideal, both for maximizing cell life, and for reducing potential stray currents in the water driving corrosion. This seems feasible to me, anyone have any thoughts? The obvious question to me would be whether this has any advantage over just using a bromine floatie? Doing that doesn't require adding a pile of salt to the water.

I’m wondering the same thing. Did you do this? How did it work. Swcg and bromine seems like a great combination.

 

[Mdragger88]

I’m wondering the same thing. Did you do this? How did it work. Swcg and bromine seems like a great combination.

It’s a bit more trouble, more complicated, & more expensive than just using chlorine & swcg alone. With a swcg the bulk of the dosing is already taken care of which is really the only appeal of bromine in my opinion (less frequent dosing) .
Many people also find bromine to be harsh & more smelly than chlorine- YMMV.
Bromine is kinda the 3rd wheel in this situation.
It can certainly be done but is unnecessarily more complicated.

 

[DrNinjaman]

It’s a bit more trouble, more complicated, & more expensive than just using chlorine & swcg alone. With a swcg the bulk of the dosing is already taken care of which is really the only appeal of bromine in my opinion (less frequent dosing) .
Many people also find bromine to be harsh & more smelly than chlorine- YMMV.
Bromine is kinda the 3rd wheel in this situation.
It can certainly be done but is unnecessarily more complicated.

So I've been looking at how my spa is running and considering the various pieces of advice I've seen on this forum and elsewhere, for example the Taylor test kit booklet and I have another potential reason for doing this. Bromine is acidic, like chlorine is, but as a sanitizer it is effective at higher pH levels, like, way higher. Bromine is something like 75% active sanitizer at pH of 8.0, while chlorine would be only 25% effective. That would suggest that a bromine pool or spa could be maintained to be less corrosive, since acidity/low pH has to be what's driving a healthy amount of the corrosion, right?

I've seen people discussing the relationship between total alkalinity and pH as well. All the water balance recommendations say to keep total alkalinity above 60ppm, but adding acid to bring water pH down destroys alkalinity directly. So am I supposed to be constantly living in the transition between pH too high, but healthy amount of TA, or pH perfect but TA too low? Then, on top of that, the Taylor book makes mention of the CYA and borate correction to TA. Apparently both borate and CYA can fool the TA test into reporting more TA than is actually present, and you are supposed to apply a correction for that.
At 30ppm borate and 30ppm CYA and 7.8 pH, the TA correction for those two together is 17.7ppm. That means if my TA test says I have 60 ppm TA at 7.8 pH, I actually have 42.3ppm.
So that's kind of alarming too. Apparently the only way to keep my pH stable at around 7.6 pH is to keep my actual true TA level at like 30ppm.

Is that a problem? I don't know. I have had to put in a lot of new heaters in a fairly short time, but there were definitely other mistakes made. I guess the notion of a bromine tub oxidized by my SWCG allowing me to leave the pH levels at 8.0 without worrying about reducing the sanitizer effectiveness appeals to me. I can keep the TA levels where recommended keep the pH higher, and since my tap calcium hardness is around 120, not have to worry about scale build-up either. Or maybe I'm worrying too much.

 

[wayner]

My understanding is that TA doesn't matter in and of itself. You only care about TA because it helps to buffer your pH. But if your pH stays pretty constant then you don't have to care about TA. I have a SWCG and chlorine salt in my tub and I can't keep pH in the proper range and TA above 50. So I live with TA at 30 and pH at 7.5.

 

[Mdragger88]

So I've been looking at how my spa is running and considering the various pieces of advice I've seen on this forum and elsewhere, for example the Taylor test kit booklet and I have another potential reason for doing this.

Ok, I’ll try to clear some things up -

Bromine is acidic, like chlorine is, but as a sanitizer it is effective at higher pH levels, like, way higher. Bromine is something like 75% active sanitizer at pH of 8.0, while chlorine would be only 25% effective. That would suggest that a bromine pool or spa could be maintained to be less corrosive, since acidity/low pH has to be what's driving a healthy amount of the corrosion, right?

This doesn’t make any sense logically- your 1st statement is sort of true, bromine (sodium bromide) is acidic
This means you must keep an eye out that you don’t tank your ph with it leading to corrosive water condition.
Some forms of chlorine are acidic (dichlor & trichlor) while liquid chlorine is not.
These things mean that the opposite of your last statement is true.
if using chlorine how we recommend (dichlor then bleach method) then your ph wouldn’t be at risk of being too low simply by keeping your water sanitized normally.

Your statement about the ph & chlorine effectiveness is not quite accurate if there’s any cya in the water at all as we recommend - I certainly wouldn’t base my sanitizer choice on this notion.

PH - Further Reading

www.troublefreepool.com

I've seen people discussing the relationship between total alkalinity and pH as well. All the water balance recommendations say to keep total alkalinity above 60ppm, but adding acid to bring water pH down destroys alkalinity directly. So am I supposed to be constantly living in the transition between pH too high, but healthy amount of TA, or pH perfect but TA too low?

There’s no need to adjust ta unless it falls below 50.
Aiming for a ph in the mid to high 7’s when it rises to 8 or above should prevent this from occurring regularly.
There is no perfect ph - any ph in the 7’s is fine really.

Then, on top of that, the Taylor book makes mention of the CYA and borate correction to TA. Apparently both borate and CYA can fool the TA test into reporting more TA than is actually present, and you are supposed to apply a correction for that.
At 30ppm borate and 30ppm CYA and 7.8 pH, the TA correction for those two together is 17.7ppm. That means if my TA test says I have 60 ppm TA at 7.8 pH, I actually have 42.3ppm.
So that's kind of alarming too. Apparently the only way to keep my pH stable at around 7.6 pH is to keep my actual true TA level at like 30ppm.

That is “adjusted Ta”
Ignore that & use your tested TA (which is your actual TA)
&
PoolMath it does all those calculations automatically so long as you have all your parameters entered.

Is that a problem? I don't know. I have had to put in a lot of new heaters in a fairly short time, but there were definitely other mistakes made. I guess the notion of a bromine tub oxidized by my SWCG allowing me to leave the pH levels at 8.0 without worrying about reducing the sanitizer effectiveness appeals to me. I can keep the TA levels where recommended keep the pH higher, and since my tap calcium hardness is around 120, not have to worry about scale build-up either. Or maybe I'm worrying too much.

Constantly high ph (above 8) & higher ch levels (200+)
increase the risk of scale &
Low ph (below 7) increases the risk of corrosion no matter what sanitizer you are using.
You are correlating things that aren’t necessarily directly connected.
Its true that Blind sodium bromide use & blind dichlor use can both lead to very low ph & ta because they are acidic.
Its also true that using liquid chlorine &/or a swcg doesn’t have these acidic effects so if ph isn’t monitored it could stay too high leading to scaling conditions.

In a spa nothing ever truly stabilizes- there is a very high sanitizer demand that must be monitored & fed continuously.
& the large amount of aeration means continuous monitoring/adjustment of ph.

 

[DavidLast]

I think, reading this, the issue is the heater damage.

I am not familiar with this spa, is the heater electrical with a stainless external?

But yes Bromine can be run with salt chlorinators. I am not sure there is an advantage for corrosion though, it may not be as effective as thought.

 

[DrNinjaman]

Ok, I’ll try to clear some things up -

This doesn’t make any sense logically- your 1st statement is sort of true, bromine (sodium bromide) is acidic
This means you must keep an eye out that you don’t tank your ph with it leading to corrosive water condition.
Some forms of chlorine are acidic (dichlor & trichlor) while liquid chlorine is not.
These things mean that the opposite of your last statement is true.
if using chlorine how we recommend (dichlor then bleach method) then your ph wouldn’t be at risk of being too low simply by keeping your water sanitized normally.

Your statement about the ph & chlorine effectiveness is not quite accurate if there’s any cya in the water at all as we recommend - I certainly wouldn’t base my sanitizer choice on this notion.

PH - Further Reading

www.troublefreepool.com

There’s no need to adjust ta unless it falls below 50.
Aiming for a ph in the mid to high 7’s when it rises to 8 or above should prevent this from occurring regularly.
There is no perfect ph - any ph in the 7’s is fine really.

That is “adjusted Ta”
Ignore that & use your tested TA (which is your actual TA)
&
PoolMath it does all those calculations automatically so long as you have all your parameters entered.

Constantly high ph (above 8) & higher ch levels (200+)
increase the risk of scale &
Low ph (below 7) increases the risk of corrosion no matter what sanitizer you are using.
You are correlating things that aren’t necessarily directly connected.
Its true that Blind sodium bromide use & blind dichlor use can both lead to very low ph & ta because they are acidic.
Its also true that using liquid chlorine &/or a swcg doesn’t have these acidic effects so if ph isn’t monitored it could stay too high leading to scaling conditions.

In a spa nothing ever truly stabilizes- there is a very high sanitizer demand that must be monitored & fed continuously.
& the large amount of aeration means continuous monitoring/adjustment of ph.

Thanks, that is helpful. So to sum up, I'm worrying too much. That's what I figured.
I was aware that CYA buffered the effect of pH on chlorine, I know I have read that before in one form or another, I just forgot how effective it is at doing so. I do keep everything at the recommended levels and have gotten quite a bit better at getting it balanced quickly after a fresh fill, I just get a little jumpy sometimes because Pool Math will tell me I have a CSI of -.6 or something and that gets me worrying about corrosion. That's the main reason I used to add calcium chloride, and since I didn't this last fill, I'm a little jumpy whenever I enter my test results into Pool Math. When my CH was 250, my csi numbers would look good too and I wouldn't have anything to worry about.
It's nerve wracking to have multiple sources of guidance for something for which I am not expert, and have some of them saying there is a problem while others say I'm okay. I trust this forum the most, but it's still anxiety inducing to ignore test results that are out of range. Especially with putting two heaters in in 16 months or so. I'm pretty sure I know why that happened, but I won't know for sure until the next one fails, hopefully several years from now.

It would help if Pool Math had a hot tub mode, so it would tell me that CYA of 30 and TA of 40 is okay though, but I suppose I can live with it as it is. I may just occasionally post random anxieties that you good folks have to look at every so often.

 

[Mdragger88]

With a standalone tub that is fiberglass or acrylic you don’t need to worry too much about a negative csi (the corrosion warning is in regards to plaster/ concrete surfaces)
A high csi on the other hand means more potential for scale on all surfaces.
Be more concerned with ph & keeping it in the 7’s & you’ll be A ok

 

[DavidLast]

Especially with putting two heaters in in 16 months or so. I'm pretty sure I know why that happened, but I won't know for sure until the next one fails, hopefully several years from now.

Adding to this complex situation, and not meaning to, gas heater failure is often blamed on chemistry and, in fact, is caused by other issues.

 

[DrNinjaman]

Adding to this complex situation, and not meaning to, gas heater failure is often blamed on chemistry and, in fact, is caused by other issues.

As I have discussed in a previous post, I suspect the accelerated heater (electric element heater) corrosion was due to my placement of the chlorine generator cell inside the return filter, so that the concentrated chlorine was funneled directly through the circ pump and heater, without diluting in the spa water. It seemed like a good idea at the time, akin to an inline install.

 

[DrNinjaman]

With a standalone tub that is fiberglass or acrylic you don’t need to worry too much about a negative csi (the corrosion warning is in regards to plaster/ concrete surfaces)
A high csi on the other hand means more potential for scale on all surfaces.
Be more concerned with ph & keeping it in the 7’s & you’ll be A ok

Keeping the pH in the 7s is exactly what I'm concerned with. While also not running out of TA. And yeah, PoolMath does all those calculations automatically and it says I need to keep my TA above 50. But if I do that, my pH climbs even when I'm not using the jets. And when I said chlorine is acidic, I'm not talking about any particular product, I meant the free chlorine species that does the sanitizing, hydrochlorous acid. If I don't run the jets at all, just the circ pump for a week or so, and the salt cell is set too high so the chlorine level get too high, the water pH will fall, just from the increased chlorine concentration. Also, you said CYA helps keep chlorine effective even at higher pH levels, right? But I find this a bit confusing, because doesn't CYA also make chlorine less effective in general? So my FC levels have to be higher in general in order to keep things clean with more CYA, just like with higher pH. It seems that adding CYA is intended to buffer the water, so you trade some reactivity with having a larger reservoir of potentially available sanitizer stored in the water, right? So the levels don't move around as quickly? That's why higher pH isn't as big of a deal? Because the chlorine bank is bigger than what is immediately necessary by a healthy margin, so even at only 25% effective, it's still plenty.
And that works fine, I'm not saying that I can't keep the TA vs pH balls in the air, I'm just wondering if you might get an even more buffered and less pH sensitive behavior with a bromine sanitized tub. If CSI in the positive range is when you need to worry about scale formation, and that is heavily driven by CH, I'm just wondering if I can take advantage of my relatively soft tap water with a bromine tub and use lower sanitizer levels over a broader range of pH which could have the overall effect of reducing corrosion. It seems like that might be true, but I'm not enough of a chemist to figure it out for sure.

 

[98Poolmaster]

Did not know that. Learn something new everyday. Thanks.

I’m pretty sure MPS does the same thing I tell people not to mix bromine and chlorine it causes rashes and skin issues but to each their own