Bromine Mystery

[tub by the lake]

I finally received my Taylor 2106K testing kit, not easy to get a hold of.
Things have been going fine for my Bromine Spa since my refill about a month ago, but I was looking forward to getting real numbers for my spa, and managing it independent of my dealer.
My bromine has read around 3-6 any time I have checked it in teh alst few weeks. the water is clear, has no significant odor and my skin feels fine after I soak. So I was more than a little surpirsed to find a reading of 17.5 ppm!!! for total Bromine ( 35 drops at .5 ppm/drop), Horrified, I rechecked at the 1.25ppm/drop concentration and it was 13 drops, still over 16 ppm!!! I checked my test strip, yup, still reads about 5. So what gives?? If my spa was really at 17, wouldn't my skin notice this?? The test is for total, not free bromine, but as I understand from the taylor booklet, unlike chlorine almost all the bromine is in the active form in a spa. If this is not the case, what is the point of testing total, and not having a test for active in the 2106 Kit?? I used some "bromine starter" ina packet at fill, I have a brominator floating fairly wide open on the adjsutment, and occasioanlly have been putting in a couple tablespoons of Brominating concentrate in after a few days of use. Despite these readings I did use it with a good number of bathers for nearly an hour today, and when I tested again I got 5ppm for total bromine, tested twice, same result???? Please offer soem insight as to what is going on, this makes little sense to me.
Larry

 

[chem geek]

Combined Bromine, mostly bromamine, is also a sanitizer, so that's why they only measure Total and don't bother to distinguish between Free and Combined. Your test strips are simply wrong and that is not a surprise -- test strips are not always accurate.

High levels of either chlorine or bromine may not necessarily be that noticeable.

If your spa is 350 gallons, then if you had 3 bathers for an hour then this could use around 20 ppm FC of chlorine or around 40 ppm of bromine. The sweat and urine in a hot 104ºF tub creates a fairly large oxidizer demand. So having the bromine level drop from 17 to 5 is not at all surprising given that bather load.

Do you have an ozonator? The ozonator might be handling part of that bather load and would also be reactivating some of the bromide back to bromine. Also, the normal way to use bromine is to set the floating feeder at a fairly low setting that just maintains a fairly constant bromine level when you are not using the tub. When you soak, then you add additional oxidizer such as chlorine to shock the tub after your soak. You could do this before your soak for maximum sanitation, but then you'll be soaking in higher bromine levels which some people don't like -- though it sounds like this isn't a problem for you.

 

[tub by the lake]

Thanks for the response,
I don't have an Ozonator.
I'm trying to get my head around the Chemistry. In my tub, Bromine exists as Bromide Ion, Hypobromous acid and Bromamine, Both the Hypobromous and the Bromamine are sanitizers, and unlike Chloramines the Bromamine isn't an irritant, so I don't care much about it. My test is "Total Bromine", Is this all three forms, or just the Bromamine and the Hypobromous?? Does my test tell me about active sanitizer or the total amount to bromine in the tub. I think the goal was 30ppm when I filled it. if I had tested just after adding the Bromine starter at fill is this what my test would measure?? If an hours use with my kids, consumes from 17-5 ppm of bromine, is this depleting my bromine reserve, or just my active sanitizer? If it's depleting the reserve, where does it go?
My floater has been set as you say to keep the level at 3-5, but this was based on my test strips, which may be meaningless. I was putting in ( SpaGuard) Brominating concentrate after use to bring the level back up to around 10 after uses, though again this was based on test strips, so who knows what it was going to. I think this product is both chlorine and some bromine, though I don't have it in front of me to check.
I don't see any signs damage on my tub, or our bodies, am I likely to have caused any by running very high bromine levels all this time?
Larry

 

[Melt In The Sun]

Your test measures bromine, not bromide. Your "bromine reserve" would be more typically called the bromide bank (your 30 ppm target). When you add chlorine, some of your bromide bank is oxidized by the chlorine and converted to bromine, which is your active sanitizer. Make sense?

 

[tub by the lake]

Spam from Bromine Mystery Thread

Yes I think that does, so the "Total Bromine" is the Combined (Bromamines), and the Hypobromous, both of which are active sanitizers. The Bromide bank I set up at fill is unmeasured ( unmeasurable?) and stays in the tub once it's there. I can activate the bromide Ions with chlorine. So why do I need a product like the Brominating concentrate at all, why not just keep activating with chlorine? Is my Bromide Bank just expanding without limit by more and more from the floater and the concentrate I am adding? Is this a problem??

 

[Melt In The Sun]

I think that's right; the "brominating concentrate" will keep adding to your bromide bank. I don't know if that's a problem or not. Once you have a sufficient bromide bank, you just need to add chlorine (or some other oxidizer) to activate it.

 

[chem geek]

Some of the bromine escapes as bromine gas, some gets carried out in swimsuits with water, some may combine with some organics and not get oxidized further. However, it's true that once you have a reasonable bromide bank to start with, you can just use bleach to reactivate the bromide to bromine and shouldn't need to add brominating concentrate -- or at least not very often. Perhaps after some number of months you might need to add more to the bromide bank, but you probably don't need to at all since you've got bromine tabs in a feeder and that will increase the bromide bank as well when the bromine gets used up oxidizing bather waste.

Unfortunately, there isn't a residential test kit that can distinguish between chloride and bromide salts. So you can't really know your bromide bank. So between now knowing chloride vs. bromide or between chlorine vs. bromine, one just has to assume it's bromine if you put enough bromide in to start with. If you can distinguish the smell, then that's a way to tell (i.e. bromine smell vs. chlorine bleach smell) as they do smell a bit different. In fact, some people don't like the smell of bromine while others prefer it to chlorine.

 

[tub by the lake]

I'm guessing that there are no equivalent slow release chlorine tablets that would maintain my active sanitizer level, or somebody would have suggested I use them instead of (more expensive and unnecessary) bromine tablets by now, so I guess I'll keep using them in the floater ( though maybe way less of them now that I know the real sanitizer levels). And use chlorine to shock from time to time.
Also, I'm trying to recall now why I still need to shock if the Bromamines it would get rid of are harmless, and still effective sanitizers?
Larry

 

[chem geek]

You are right that there are no equivalent slow releasing tablets for chlorine in a spa. Trichlor pucks/tabs are used in pools, but generally aren't used in spas because they dissolve too quickly in hot water and are quite acidic. Nevertheless, I have seen some people use some tiny Trichlor pucks in a special floating feeder for spas so I know it does exist -- it's just not very common. Of course, for every 10 ppm FC from the Trichlor, it will increase CYA by 6 ppm so eventually the CYA will get too high, but at least it grows more slowly than with Dichlor.

You are correct that you really don't need to shock the spa. You only need to add some oxidizer (such as bleach) to reactivate the bromine if it gets too low -- usually you just do this after a soak since the bather waste will require more bromine.

 

[tub by the lake]

Typical use for this tub is to sit idle for 5 or days at the cabin, then get very heavy use for a day or 2, with little kids. If I bring the level back up to 3-5 after use with bleach, then leave the brominator to do it's thing and try and hold that level is that sufficient? Will there be a delayed drop in Bromine some time after we get out of the tub (as sanitizer is consumed?) that we should try and compensate for with higher levels of bromine right after we get out, or would we see whatever effect of our use is right away?
By the way thanks for the help so far. Without this site, I'd be running Bromine levels around twenty forever, millions of others must be.
Larry

 

[chem geek]

I would set the brominating tabs floating feeder such that your bromine levels are fairly low but consistent -- around 3 ppm bromine. However, after using the tub, you need to add a LOT more bleach than you are using. The rough rule-of-thumb is that every person-hour of soaking in a hot (104ºF) tub needs around 5 fluid ounces of 6% bleach (that's around 7 ppm FC or 15-16 ppm bromine in 350 gallons). I'd use half the amount based on your bather load and see if the measurement that spikes when you add the bleach goes down to a lower level after a day of non-use.

 

[tub by the lake]

Does this mean that after 1 person*hour of soaking that a 350 gal tub that was at 3ppm Bromine will be at zero Bromine, in fact less than zero as it will take about some ( how much?) of that 5 oz. of bleach added afterward just to get back to zero sanitizer, and the rest to overshoot a bit?? What is my target Bromine level after a post soak bleach addition, when should I check it? Immediately after adding the bleach? An hour later? More??

 

[chem geek]

Unfortunately with bromine it's more complicated because bromine combined with ammonia from sweat and urine is bromamine that is still a decent sanitizer so the test kits just measure Total Bromine and not Free Bromine. So you may still measure a bromine level after a soak plus there will be extra bather waste (ammonia and urea, mostly) left unoxidized. With enough bromine, the bromamine can get oxidized by bromine to become bromide salt. So where you actually end up is more difficult to know than when using chlorine where the FC level is an easier guide to actual sanitizer demand.

If you add an oxidizer, such as bleach, to the tub and an hour later the bromine level hasn't gone up as expected, then that's a sign that there is more bather load and bromamine left to oxidize. When you add bleach and an hour later the bromine level has risen by what you expected, then that may mean that you've "caught up" though it could also mean you've got so much bather waste that you are just forming bromamine.

This is a conundrum that I'll have to think about to see if there's some better test that can be used as a more reliable guide. Most people don't worry about this and just make sure they are always measuring Total Bromine levels since that is what is important for sanitation, but it may mean that they are soaking in water with a combination of bromamine and extra bather waste (ammonia and urea) which is still sanitary but does have a sort of "yuck" factor if you think about it.

 

[tub by the lake]

The more I learn the less I seem to know.
What would you expect the total bromine to do as a result of use, go down or stay constant? Use introduces organics that combine to to form bromamines but they are measured within total bromine, they are still good sanitizers and they are harmless, so who cares how much of the total bromine is in hypobromous vs. bromamines. If it goes down, where does it go? to Bromide not measured in total bromine, but ready to be reactivated with an oxidizer, or out of the tub as bromine gas?
Larry

 

[chem geek]

The process goes something like this:

Start with sodium bromide (i.e. the bromide "bank").
Add either an oxidizer such as chlorine or use bromine tabs -- either way you end up with some bromine. Technically this is hypobromous acid (HOBr), but I'll just call it bromine.
Chlorine + Bromide ---> Bromine (+ Chloride)
... OR
Bromine Tabs ---> Bromine

Now introduce some bather waste -- I'll use ammonia specifically in this example.
Bromine + ammonia ---> Bromamine

At this point, the Total Bromine you measure is a combination of whatever bromine is left plus bromamine. The above reaction is very fast, in seconds. Now add more oxidizer to produce more bromine and then have that oxidize bromamine:

Chlorine + Bromide ---> Bromine (+ Chloride)
Bromine + Bromamine ---> Bromide + Nitrogen Gas (+ Hydrogen Ion)

The above reaction oxidizing bromamine is somewhat slow taking at least 10 minutes to an hour. So with sufficient bromine added/created, you get rid of the bromamine and it reverts back to bromide. The Total Bromine at this point gets to zero if all of the bromamine is gone. If you add more oxidizer (chlorine), then you produce bromine:

Chlorine + Bromide ---> Bromine (+ Chloride)

So if you have bather waste and you add oxidizer after a soak, the Total Bromine at first rises due to producing bromine and then bromamine and then it drops as that bromamine is oxidized. If you add enough oxidizer, then there is bromine leftover showing up as Total Bromine. The problem is that it is hard to know if one has added enough.

I'm going to find out if an ammonia test kit, which technically adds chlorine to the ammonia to produce monochloramine and then measures monochloramine, can measure the monobromamine. If it can, then that would be a decent test to see if one is "behind" and needs more oxidizer (chlorine).

 

[geekgranny]

When I switched to Bromine 3-step, I had a heck of a time keeping my bromine levels low enough. And yes, you can certainly smell the bromine. I'm one who likes the smell of chlorine over the smell of very high levels of bromine.

I just drained and refilled my spa and the only reason I'm sticking with bromine is that I have a lot and want to use it up. Then I'm switching back to chlorine. I couldn't get to doing the other adjustments, yesterday, so I'm probably going to have to wait a day or more, or use some bromine neutralizer, to test and adjust other values.

I purchased the neutralizer just becuase I frequently have excess bromine reading. As the water got "older" it was easier to keep in line.

Does neutralizer "destroy" the bromine in the bank or temporarily inactivate it?

My ozonator works intermittently so it makes keeping levels even more difficult. I'm taking it out of the system today.

gg=alice

 

[chem geek]

Neutralizer will convert bromine to bromide thereby increasing your bromide bank. It does a similar thing to chlorine converting it to chloride (salt).

 

[geekgranny]

Neutralizer will convert bromine to bromide thereby increasing your bromide bank. It does a similar thing to chlorine converting it to chloride (salt).

Thanks much. Well, this fill is a different story. Day before yesterday, evening, I add the proper amount for bank and put floater in, as before, set to the same setting, as before. But didn't do any other adjustments to fresh fill water. When I checked the level yesterday, bromine was within target range.

Still haven't take ozonator out yet but will yank it today. This time vs last times after converting to bromine, I'm going to do other adjustments of chems over a two day period adding only partial amounts, as call for, from The Calculator at a time, one chem at a time till I reach target for each. I think that is partially what screwed up my initial adjusting, on refill, other times. Too much and too many at one time.

As long as I keep the sanitizer in range, I really don't have to hurry up the other additions.... within reasonable time; like 36 hours. Right?

gg=alice

 

[tub by the lake]

chemgeek,
thanks again. I'm starting to get my head around it all now. I'm seeing ( unintentionally) very high total bromine levels now come down shortly after I'm in with the kids. Not surprising considering likely huge quantities of..., lets just say nitrogenous wastes...
So my bromine is combining with them to form bromamine, that step is nearly instant, and does not in itself lower my total bromine level, but concurrently and more slowly some of this bromamine is being oxidized by the remaining bromine which has not combined, and the resulting bromide goes back into the bank and my test levels drop off. If I do nothing now and if there is enough waste in the water the levels will fall toward zero over an hour or so. I can add chlorine ( liquid bleach) to bring bromine back out of the bank in a big hurry, which I should do rather than just let the tabs in the floater bring the level up slowly because it's not good to have the water sit around with low sanitizer levels or it grows stuff. Do have it about right?
I'm still working on a testable goal for this post swim chlorine addition, and the timing of it. Since total bromine is all I can measure, and it will fall for maybe an hour or so after we get out as the bromine works on the bromamine, how high do I want the bromine test to be and when should i test it? I can add some bleach right away and test an hour later and see if I added enough. What do I want to see to show that I have? Do I want to overshoot to a high bromine level, or is it enough to be in the 3-5 range an hour later. Is this a long enough interval? Will there be remaining bromamines causing a further decline into low sani-levels?
I'm trying to work out some recipes that work as we typically do what we did this morning, after a swim, I put in 2 oz. of 6% bleach and we left almost right away and I won't be back up to test it for several days. So the idea of add a bit, test, repeat a few times, though sensible won't be achievable most days. I put in the bleach, and dropped in the floater closed down more than before as levels were always to high previously, and I'm hoping for the best on my return later this week.
And one more thing, Do I ever need really high levels or bromine (shock) to get rid of the bromamines, ( if I even care to get rid of them), or will they be worked on by the bromine that is around when levels are in the 3-5 range?
Larry

 

[chem geek]

Yes you've got the understanding exactly right.

As for how much chlorine to add after a soak, if you don't have the ozonator then the rough rule-of-thumb I gave of 5 fluid ounces of 6% bleach per person-hour of soaking (at hot 104ºF temps) is probably about right, though may be conservative. With an ozonator, the amount would probably be half this much or perhaps even less.

As for your question about the bromamines, by themselves they aren't a problem since they sanitize reasonably well (unlike chloramine) but I don't believe they oxidize ammonia which means that further soaking would build up ammonia (and urea) if all you had were bromamines and no bromine. Since the test kit doesn't distinguish between these, you can't tell whether there is some bromine available to get rid of some of the bromamines except by seeing the Total Bromine level drop over around an hour.

Until I figure out some sort of more definitive test you can do, you can use the rough rule-of-thumb and just see what the Total Bromine level is like before the next soak. If it's too high, then use less chlorine after a soak. If it gets too low, use more.