Bromine Chemistry Question

[FormerBromineUser]

I know that this is not really a bromine chemistry site but I am hoping there are some chemists out there.... I have a bromine pool that has a cya level of around 35 (long story). I have been told that I cannot maintain a bromine residual because the cya level is above 25 as the cya is preventing chlorine from activating my bromine. Does this make any sense to anyone?

[PoolDoc]

Yeah. But what makes more sense is that you don't understand how bromine works. Not that you would -- it's a secret well-hidden by the pool industry. Far be it from them, to bad-mouth any pool product that's making somebody money, no matter how bad it is for the consumer.

1. CYA does NOT prevent chlorine from 'activating' bromide to bromine. Jock Hamilton, who started United Chemical, created an entire line of chemicals based on the fact that over-stabilized chlorine (CYA > 100 ppm) DOES 'activate' bromide.

2. Likely, you've gotten this info from the same source that sold you on the idea that bromine is a useful sanitizer for outdoor pools? This should give you a clue about their 'expertise'.

3. The *only* reason that bromine is sold for regular use on outdoor pools, is that it made certain companies more money than chlorine would have. It is a weaker sanitizer. It cannot be stabilized, so loss rates under full sun are horrendous. And, it is much more expensive. Outdoors, it is not better than chlorine in any respect. (There is some justification for using of bromide, as a 'rescue' for over-stabilized pools. It's just that it's a better and cheaper solution to simply get an FAS-DPD test kit, and raise chlorine levels appropriately to compensate! But, FAS-DPD testing didn't exist when Jock Hamilton started United.)

4. Most 'bromine' used on outdoor pools arrives as white tablets or sticks made of "BCDMH" -- bromo-chloro-dimethyl-hydantoin. You may notice the "chloro" bit? Bromine is too expensive to sell, even with the aggressive marketing campaigns that have been employed. So, to cut costs 1/2 of the 'sanitizing' effect of your "bromine" comes from chlorine!

5. Now, after you've used BCDMH, you've built up a substantial bromide residual. The reason is, when bromine is used up, it (mostly) turns into bromide. Likewise, when chlorine is used up, it (mostly) turns into chloride (salt!). So, after a while, the chlorine in the BCDMH instantly reacts with the bromide, converting it to bromine. In the process, the chlorine becomes chloride.

6. What your profit-seeking BCDMH sales predators won't tell you is, at that point, you no longer need any bromine, to have a brominated pool! The reason is that you can now brominate your pool simply by adding chlorine -- in any form -- and it will convert bromide to bromine. In other words, you no longer need to by half-n-half BCDMH; you can simply use a product that is only chlorine. . . . like PLAIN 8.25% household bleach.

7. Your local sales predator, will be horrified, and may tell you that you'll no longer have bromine. So, ask him this: how would he know? Because there is NO field test (or pool store test) that can tell the difference between chlorine and bromine. You put 1 ppm chlorine into water and test it with a chlorine test kit -- it will show 1 ppm. Test it with a bromine test kit, and it will show 2.25 ppm Conversely, if you put 2.25 ppm of bromine into water, and test with a bromine kit, you'll find 2.25 ppm. (Surprise!) But if you test it with a chlorine test kit . . . . you'll find 1 ppm chlorine. I could explain why, but I'd have to talk about relative molecular weights and ppm vs molarity. That's not stuff most people want to hear about.

8. There are likely two reasons why you "can't maintain a bromine residual".
(a) Your chlorine demand is up, possibly because of more swimmers, but more likely because of algae.
(b) You are finally getting some sunshine and, unlike chlorine, bromine can't be stabilized!

The problem could be (a) or (b) or both. Regardless, the solution is to add more chlorine till
(a) the algae is gone, and
(b) you are keeping up with the sunshine.

[FormerBromineUser]

Wow...... That's an amazing reply! Thank you so much for taking the time, energy, and thoughtfulness to put it together.

You are right about having a chlorine demand, I do, and there are details below if you're interested in how broke I am trying to fix it. :-)

I will try to find somewhere that will sell me a trunk-load of regular household bleach. My pool guys say that I have to add the demand-dose all at once or it's a waste as small doses will be ineffective. Is this true? How do I decide how much bleach to use?

Just for background, I have around a 30,000 gallon vinyl-liner pool. I had perfect sanitizer readings between 2-5 from opening through all summer adding 6oz of metal magnet, 6 oz algaecide, 6 oz clarifier, and 3 lbs of oxy-sheen each week.....until two things happened three weeks ago. One, my automatic pool cover broke so the pool is exposed to the sun and two, I left town for a long weekend. When I returned, my sanitizer readings were zero.

I have hardly had ANY swimmers this summer due to our cold temperatures. All were adults except for a total of 10 hours by some pee-respectful 12 year olds. (No ammonia shows on pool sample tests). My algacide levels are so high that the store recommended I stop regular maintenance for a while; same thing with my sequest (metal magnet). And yes, we have checked the sand and filtration. The water is clear and looks perfect except it doesn't have that sparkly shimmer when the water is absolutely perfect.

So according to what you said, the problem may very well be a combination of sun and algae. If it's algae, then with my algaecide levels so high and the amount of chlorine I have already put in, it must be an invisible and indestructible algae!!!

Now want to hear about what a money-maker I have been for my pool store? In their defense, they told me the bit about how testing for chlorine/bromine (sanitizer) works as well as the bit about the presence of chlorine in the bromine tabs. Also, when they built the pool, I was the one who asked to use bromine as my son used to get rashes and huge rings around his eyes whenever he was in chlorine pools and our doctor said it was an allergic reaction. Anyway, here's my life for the last three weeks:

-First we used 12 plus lbs of Burn-out 35. Back to zero within 3 days.
-Then we used 24 lbs of Burn-out 3. Back to zero within a few days.
-They did a chlorine demand test which called for 54 lbs of Burn-out. I used 64 lbs. Sixty-four! Back to zero.
-Another demand test still called for over 50 lbs of Burn-out. We used 40 gallons of their liquid chlorine (around 12% or something). Back to zero with the same demand.
-Then they GAVE me 20 gallons of liquid. Back to zero with same demand.
-Then they ran a phosphate test with results of almost 1000. I used Bioguard's pool tonic (also on the house). Still almost 1000.
-Then I used SeaKlear's phosphate remover that was supposed to be stronger and cost around 50 bucks! You guessed it, still 1000 and my chlorine demand remains.
-The Bioguard rep was in today from Atlanta and he called his chemical guru who said the bit about cya and recommended draining the pool about two feet hoping to get the cya below 25 and then re-running the chlorine demand test.

[chem geek]

It sounds to me like you had a bacterial conversion of CYA into ammonia when the bromine level went to zero. Did you notice the CYA level drop from before you left until after you came back and noticed the zero bromine level? That can create a huge oxidizer demand. For every 10 ppm CYA drop, it creates a nearly 30 ppm FC chlorine demand. The following is what you added in FC for a 30,000 gallon pool:

12 pounds of Burn-out 35 (Lithium Hypochlorite with 35% Available Chlorine): 17 ppm FC
24 pounds of Burn-out 3 (57.8% Cal-Hypo): 55 ppm FC
64 pound of Burn-out (you didn't say which type was used -- I'll assume it was 35 so lithium hypochlorite): 89 ppm FC
40 gallons of 12.5% chlorinating liquid: 160 ppm FC
20 gallons of 12.5% chlorinating liquid: 80 ppm FC

So that is a total cumulative demand of around 400 ppm FC. Such a demand can come from bacterial conversion of 133 ppm CYA into ammonia. Was your CYA high before you left? You said it was 35 ppm, but how did you know it's level? If you used Dichlor to activate your bromine then the CYA level can get very high because for every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.

See Degradation of Cyanuric Acid (CYA) for technical details and It Can Happen to Anyone - Zero Chlorine, CYA-->Ammonia for my personal experience with this phenomenon. Did anyone bother to do an ammonia test? If your bromine level is still zero, you can get an inexpensive ammonia test kit from a fish/aquarium/pet store since that would help to confirm the problem and also give you an idea of how much more oxidizer you are going to need, though a properly-done demand test would tell you that (it sounds like they didn't do their demand tests properly).

I also assume they aren't doing something stupid like raising the bromine level so high as to bleach out their DPD tests and then thinking that there isn't any bromine in the pool when there is actually too much bromine in the pool. Do you have an OTO chlorine/bromine test you can use for confirmation?

[FormerBromineUser]

My, my. I was hoping for a chemist but now I'm a little embarrassed... I have almost no idea what you're talking about!

I will try to respond in the same order that you wrote. First, they haven't checked for CYA until the other day as it is their standard practice not to check CYA for bromine pools. I have not added any stabilizer since last year when a new employee had me use Super Soluble.

The store has checked my ammonia levels all summer and have only once found a small amount. It was gone within a few days. They have never given me any numbers but they always say "no ammonia".

The 64 lb treatment was Burn-out 3.

To my knowledge I have never used anything called Dichlor except that it was in the Super Soluble that I used last year as: "Sodium dichloro-s-triainetrione dihydrate"

I have no reason to doubt their ammonia tests as they always seem a bit confused that I don't have any. I think it would help things out if I did....

Why do you think the demand tests were done improperly? Because the demand wasn't met?

And as to raising bromine levels, to my knowledge, the only thing I do that adds bromine are the tabs. I have my Pentair in-line feeder set at 5 which is the highest level it goes and I top it off every 4 days or so and in the last three weeks, every other day.

No, I do not have an OTO kit. I use Aquacheck bromine strips at home. As the pool store is only 5 miles from me, it is convenient to just have them test on their ALEX system.

I am much comforted that PoolDoc and Chem_Geek are responding. I feel like I have the big guns in my corner. :-)

[BigDave]

No ammonia and lots and lots and lots of chlorine. I think Chem Geek's onto something. Please pick up an OTO drops kit and test the pool water. Tell us what color you see.

[FormerBromineUser]

Thank you for your help, BigDave! I had hoped I would hear again from Chem_Geek as I ASSUMED that he didn't notice (in my long diatribe) that my pool store said I don't have an ammonia issue or that I never added stabilizer this year so I couldn't be converting CYA to ammonia. Maybe he was saying I DO have ammonia but that the heavy chlorine doses are knocking it out by the time it's tested? I am SO confused!!!! I will go get my own ammonia kit from a pet store but so far I can't seem to find an OTO kit. If I don't find one tomorrow, I will get one on-line and if so, results may take awhile.

[PoolDoc]

I don't think it really matters that much, whether it's ammonia, bromide, or algae: in all three cases, the solution is consistent chlorinination + sunlight.

It would help if you get a Taylor K2006 from Amazon and test your pool's water with it. That information would enable more specific recommendations. There's a testkit info page linked in my blue signature block, below.

For what it's worth: your doctor is mistaken; there's apparently no such thing a a chlorine allergy. "Bleach baths" (50 - 100 ppm chlorine) are used by dermatologists -- even pediatric dermatologists -- to TREAT allergic skin conditions. Google for "bleach bath" if you want to check this out.

On there other hand, there ARE confirmed dermatological (not necessarily allergic) reactions to both monochloramine (produced when using Yellow OUT) and DMH (dimethyl hydantoin) which is used as the chemical 'binder' in bromine tablets.

I'm not saying your son didn't have a reaction; just that it wasn't from chlorine. Badly managed pools, of which there are many, tend to have high levels of complex chloramines, which can be very irritating. We had a very extensive discussion on this topic last year. I can dig that up, if you like. Or, you can just ask your doctor to point you to the "journal article that reported on allergic reactions to chlorine" -- if he actually has one, it's something several of us would very much like to see.

But what we've found is that such reports seem to originate with non-specialists, who don't know as much about pool chlorine chemistry as you do.

[BigDave]

... I will go get my own ammonia kit from a pet store but so far I can't seem to find an OTO kit. If I don't find one tomorrow, I will get one on-line and if so, results may take awhile.

No need to get an OTO test online (but do order a K-2006). OTO is available almost anywhere pool stuff is sold. It's the yellow drops in the Red/Yellow drops kits - Pools store, wall mart, Home Depot, etc.

What Chem Geek was suggesting and I was seconding was that you might have extremely high chlorine level. So high that the chlorine / bromine tests are getting bleached out. OTO doesn't bleach out and will read yellow to orange to brown as chlorine / bromine concentration gets very high.

By Chem Geek's estimate, you've added about 460ppm chlorine to your pool. That's quite alot. If the CYA wasn't greater than 100 then there wasn't enough to become the chlorine demand you're seeing through conversion to ammonia.

You really need a definitive test (OTO) for extremely high chlorine.

[FormerBromineUser]

Thanks, guys, so, SO much. I was really hoping to have a sanitized pool by my party on Sunday but I'm sol on that.... I can still see the main drain clearly but the intervening water is getting grayer and grayer. Less than 48 hours to go and counting!

Based on Ben's suggestion early on, I have added nine 3.78 quart bottles of Clorox (8.25%) at night. In the morning, my strips are off the chart (>20 dark green) for chlorine but by afternoon, zero. That's why I don't understand this: "What Chem Geek was suggesting and I was seconding was that you might have extremely high chlorine level. So high that the chlorine / bromine tests are getting bleached out." Why would I get readings after adding beach? I am so confused. Also, after I add chlorine, I can smell it. When I can't, the strips read zero. I think the sunlight is stealing everything I pour in. In the past when I accidentally let my tabs get low, I super-chlorinated and the pool bounced back so that I only used bromine tabs and oxy-sheen oxidizer; no straight chlorine. The bromine tabs seemed to survive the sun but then again, the auto-cover worked and I closed it when the pool was not in use.

You all know so much more than I do. To me, the following is incomprehensible: " If the CYA wasn't greater than 100 then there wasn't enough to become the chlorine demand you're seeing through conversion to ammonia." My mind keeps saying that I don't have ammonia so what the heck are they talking about. Btw, I checked my local HomeDepot, Walmart, Target.... Not one had OTO kits, just refills. It's just as well as now I will just get the Taylor K2006.

Ben, I wanted to let you know that years ago I realized that my son's doctor was wrong. I had only mentioned the issue in order to accept responsibility for the bromine vs. chlorine decision when we built our pool back in '05. My pool guys are not perfect but the bromine call was mine, not theirs... Also, I read how you receive a commission from amazon by folks linking through you. I have already bookmarked your link as my way onto amazon's site. I only spend about a thou at amazon each year but I hope my part helps. I appreciate all you have done for me and all the many, many people on poolforum. What a great service you all provide.