Bromine Chemistry Question

[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.

[chem geek]

So the fact that your strips were off the chart after adding the chlorine but then it was all gone by the afternoon may indicate something in the water with a huge chlorine demand still present. Next time you do this, add the chlorine at night after the sun is down, measure it within 30 minutes (with the pump running), keep the pump running overnight and measure the chlorine/bromine in the morning. That will eliminate the possibility of it going away from sunlight due to a lack of CYA (though the measurements showed some CYA, but I don't trust test strips, especially not for CYA).

As for previously having a high CYA level before this problem started, I think that very likely if you were using

Super Soluble that I used last year as: "Sodium dichloro-s-triainetrione dihydrate"

since that is Dichlor where for every 10 ppm FC that you added, it also increased CYA by 9 ppm. So unless you had a lot of water dilution, your CYA may indeed have been very high. And as I noted, you roughly triple the CYA level that dropped to get the FC chlorine demand that could result if bacteria converted the CYA into ammonia. I'm not sure if I trust the pool store with their ammonia test, though as Ben says it doesn't really matter what the source of the demand is, eventually you can get through it with enough chlorine. I'm just concerned that it could still be an awful lot left to go. What's the volume of your pool? Perhaps it would have been easier and cheaper to replace most of the water instead.

You could do a bucket test to get an idea for the chlorine demand left in your pool -- presumably that is what the pool store was doing with their "chlorine demand test", but perhaps they weren't doing it correctly. In 2 gallons of pool water, every 1/4 teaspoon of 6% bleach will be 10 ppm FC so you can see how much of this you have to add before you register chlorine/bromine that doesn't go away.

[PoolDoc]

A couple of quick comments:

1. Get the refill kit; use the OTO in a small bottle or tube. The colors you'll be seeing aren't on the test block anyhow. When you order the K2006, order an OTO kit, too. They are useful, and cheaper for a quick test, than the K2006.

2. Keep your pH high; that will minimize the smell. Also, do test the water with the local OTO, BEFORE anyone swims. Notice whether there's much color change between the color 5 seconds after adding and mixing, and 1 minute later. If so, do NOT swim. The change indicates high chloramine levels that will be very irritating. Especially, do not let your son in the pool.

3. Tell us how long you've used bromine -- has it been since 2005? If so, you're probably going to need to plan a water change (NOT: drain -- you can't drain a vinyl pool) to remove the accumulated DMH.). But I need to check -- for all I know, it's possible that DMH can be biodegraded to ammonia in a manner analogous to what happens to cyanuric acid. If so, it may be gone. But, I don't know how to test for that.

4. You may want to look at this, about contact dermatitis due to DMH: http://www.postermedic.com/parcdesal...imas105237.pdf