Couple questions about fecal accident response

[AClogston]

I was going over the state codes for Fecal Accident Response where I live and I had a few questions.

Our indoor pool uses bromine and the state asks for the free chlorine to be raised to 20ppm and maintain for 13 hours in the event, it makes no mention of bromine levels. Is there a corresponding bumped up bromine level to be at? We use Potassium Monopersulfate shock in the pool normally, which doesn't increase free chlorine. Can we use this shock in this instance of an accident or should we have calcium hypochlorite on hand specifically for this occasion. Does the CalHypo account for the 20pp of FC?

Another question I had was about the ph during all this. It says to maintain a ph between 7.2 and 7.5 at the higher chlorine level. Say your ph was at 7.6-7.8 at the time of accident. Would you first lower the ph before superchlorinating? If so how long would you have to wait between the two.

Any help would be appreciated. Great forum!

 

[257WbyMag]

Welcome to TFP!

Are you operating a public pool? Unless I am wrong, I think that public pools are typically required to use chlorine rather than bromine. Therefore, that may explain the requirement of raising the FC to treat.

Chlorine does a better job of disinfecting when it is closer to a pH of 7.2 than it does with a pH of 7.6 to 7.8. You would first want to adjust your pH and then superchlorinate afterward. This is because pH readings can read falsely high with high FC readings.

 

[AClogston]

Thanks for the reply!

This is indeed a public pool. Bromine is an acceptable sanitizer according to the code, it must be maintained between 2-10 mg/L. Just wasn't sure what to do in this event, normally I'd just add a bunch of the non-chlorine shock, now I'm not so sure if that's the best route in a bromine pool.

If I have to adjust my ph before superchlorinating, will it take a whole turnover period to lower the ph before I can add the chlorine? I realize the best method is to have your ph in this range anyway, but I was just curious what to do in this instance.

 

[Bama Rambler]

Where are you located? If Bromine is a accepted sanitizer then there should be a paragraph in the code that handles pools using that as a sanitizer instead of chlorine. Though the action may be the same, it should be stated. If it isn't, you should call the AHJ (authority having jurisdiction) and ask them specifically what the rule is for a bromine pool.

 

[AClogston]

I'm located in New Hampshire. I've gone over the codes a few times and while there is info regarding what level the bromine should be kept at during normal operation, there is no mention of raising bromine levels in response to fecal accident, only the chlorine levels. This is why I was wondering if I had to add a chlorinated shock.

Here is a link to the state regulations:
http://des.nh.gov/organization/commissioner/legal/rules/documents/env-wq1100.pdf

Am I missing something? If I'm not I will give the DES a call.

 

[Richard320]

I looked up the Los Angeles County guidelines, just to see if they said anything, and I know I've read it before and could find it again. They don't mention Bromine, but do mention using CDC guidelines. So I looked there. The relevant section says

6.5.3.5 There are no inactivation data for Giardia or Crypto for bromine or any
developed protocols for how to hyperbrominate a swimming pool and
inactivate pathogens that may be present in fecal matter or vomit.
Therefore, pool operators should use chlorine in their disinfection
procedures. It should also be noted that DPD test kits cannot differentiate
between chlorine and bromine. This is because DPD undergoes the same
chemical reaction with both chlorine and bromine. Therefore, it is important that the pool’s bromine residual be measured before chlorine is added to the pool. This bromine residual should be taken into consideration when determining that the free chlorine residual necessary for the type of contamination has been met (i.e., the free chlorine residual measured minus the bromine residual should be equal to or greater than the intended free chlorine residual). If a DPD test kit with a chlorine comparator is used; the total bromine residual can be determined by multiplying the free chlorine residual by a factor of 2.2.

So you better keep some bleach on hand, just in case!

 

[chem geek]

(some duplicate info to Richard's post above as I wrote it at about the same time he did...)

The CDC's Fecal Incident Response Recommendations for Pool Staff does not mention bromine and I don't know of any studies showing bromine levels needed to inactivate Cyrptosporidium. Likewise, the CDC Model Aquatic Health Code (MAHC) Fecal/Vomit/Blood Contamination Response (which is in development and not yet official) gives the following not particularly helpful response:

There are no inactivation data for Giardia or Crypto for bromine or any developed protocols for how to hyperbrominate a swimming pool and inactivate pathogens that may be present in fecal matter or vomit. Therefore, pool operators should use chlorine in their disinfection procedures.

So basically you are just left with superchlorinating the pool using the chlorine guidelines, but if you are using a bromine test kit you need to divide the bromine reading by 2.25 to get the equivalent chlorine reading.

 

[AClogston]

Thanks for all the help everyone. I'm starting to get a better understanding of it now. Another question I have is can you use chlorine shocks in a bromine pool? The bromine in the pool is normally kept at a little over 6ppm, which is the chlorine equivalent of 3ppm which is the suggested level for solid stool. So I just maintain that level along with the states suggestion of "spot treating" with liquid bleach or 2 oz. granular chlorine. Can I use calcium-hypochlorite for this in my bromine pool without any adverse effects? Does it matter that I use a potassium-monopersulfate shock on a regular basis? I've read a couple places that you shouldn't use them both in the same pool. They wouldn't be mixed that's for sure, probably not even in the same week.

My outdoor chlorine pool also uses potassium monopersulfate for weekly maintenance shocking, will calhypo have any adverse effect here?

Last series of questions (famous last words), if I can in fact use calhypo in the bromine pool for disinfection purposes, does the chlorine reading "overtake" the bromine reading or start the reading over? I'll attempt to elaborate what I mean. I normally use a comparator that measures chlorine/bromine side-by-side, the bromine is usually >6ppm equivalent to 3 ppm chlorine. In that CDC document you both cite it mentions measuring and subtracting the bromine reading before determining the level to raise chlorine. When I add calhypo will it start the reading over or just get darker from where it started with the 6ppm bromine reading. And if I subtract the previous bromine level, do I only have to raise it to 17 ppm to meet requirements?

Apologies for all the rambling.

 

[chem geek]

Normally, you have enough sodium bromide in the water either added directly initially or accumulated from bromine tabs that any oxidizer added to the pool, be it chlorine or non-chlorine shock (potassium monopersulfate aka MPS) will simply oxidize the bromide to bromine. This is what is meant by "once a bromine pool, always a bromine pool". So yes, you can use Cal-Hypo, MPS or any other chlorine or oxidizer in the pool with the result that it will just end up making more bromine.

As for the test kit, it cannot distinguish between chlorine and bromine. The units of measurement are different which is why the bromine side shows double the chlorine side in the test kit. Technically, the bromine reading is 2.25 times the chlorine reading, but it is impossible for the test kit nor for you to know which it is. However, based on what I wrote above, you can pretty much be assured that what you are reading is a bromine reading.

At the end of the day, it doesn't really matter because fecal accident response just means getting the Free Chlorine (FC) reading to 20 ppm or the Total Bromine reading to 45 ppm since these are identical. A standard DPD test kit can't read that high. You'd need a FAS-DPD test kit instead and in that case the kit will tell you how many drops represents how many ppm of chlorine or bromine (depending on which kit you get).

 

[AClogston]

Thank you very much chem geek, I think I finally get it. I appreciate the help.

 

[JoshU]

Like Chem Geek said I would go through that CDC info and follow that carefully to keep compliant. Most local health departments will fall back to CDC suggestions.

 

[JamesW]

Another issue is what is the level of dimethylhydantoin? It probably has an inhibitory effect on the bromine similar to what happens with cyanuric acid and chlorine. Some jurisdictions limit the level of DMH to 200 mg/L (ppm).

How long since the pool was filled?
How many gallons is the pool?
How many pounds of bromine tabs have been used?

I think that the use of bromine tabs should be limited to what would supply 200 ppm DMH. Then you could use liquid chlorine, which would activate the bromide to bromine without adding any additional DMH. Liquid chlorine would also be more pH neutral than the acidic tabs.

 

[chem geek]

Another issue is what is the level of dimethylhydantoin? It probably has an inhibitory effect on the bromine similar to what happens with cyanuric acid and chlorine.

Have you ever found any scientific papers giving the equilibrium constants for bromine that is free vs. attached to DMH? I've seen inconsistent sources, but would really like to know this information as this issue has come up before in terms of the use of bromine tabs.

 

[JamesW]

I have not been able to find any good information regarding the equilibrium equations. I am not sure what the recommended maximum level of 200 mg/l is derived from.

It seems to me that the use of bromine tabs should generally be avoided. I think that once the bromide bank is established, then liquid chlorine could be used, and would provide a better overall water quality.

 

[AClogston]

Son of a ......

Another insidious chemical I never knew about.

I checked our state codes and it makes no mention of dimethylhydantoin at all, or of any level it should be maintained at, so I think we're okay in the compliance aspect. You said "It probably has an inhibitory effect on the bromine similar to what happens with cyanuric acid and chlorine", but is there evidence of that? The local codes and CPO handbook mention the effect of CYA on chlorine and on CT values for accidents repeatedly, but make no mention of this interaction. Is there any way to test for DMH? I take it that dilution is the only means of lowering it?

The spa gets drained pretty much weekly so I can't see a problem there, but the pool is another story. We drained it in December (due to a fire), but before that it had probably been 5 years since a complete refill (resurfacing). We normally order 50 lbs of bromine about every 3 months, keeping the pool and spa at around 6ppm, normally.

I'll probably continue with bromine in this pool/spa, but now I have a reason to distrust that as well.

 

[JamesW]

You said "It probably has an inhibitory effect on the bromine similar to what happens with cyanuric acid and chlorine", but is there evidence of that?

The level of dimethylhydantoin in the water must be limited and should not exceed 200 mg/l. There is no poolside test kit available, and the need to regularly monitor dimethylhydantoin by a qualified laboratory is a disadvantage of the use of BCDMH. Reference

The concentration of BCDMH in water should not reach 200 mg/L or higher, otherwise the equilibrium between the residual disinfectant and the organic matter is disturbed. Reference

DMH below a maximum of 200 mg/L. http://www.health.vic.gov.au/phwa/downl ... ouncil.pdf

4 Where bromochlorodimethylhydantoin is used the maximum dimethylhydantoin concentration shall be 200 mg/L. Reference

High concentrations of dimethyl hydantoin (the DMH in BCDMH) are known to build up in pools treated with bromo-chloro-dimethylhydantoin, tying up bromine and reducing effectiveness. Problems similar to those that occur in chlorinated pools overstabilized with cyanuric acid result. Reference

Excessive DMH affects the disinfection efficiency so the level must not be allowed to get too high. The concentration should not exceed 200 ppm. http://www.swimming-pool-chemicals.co.u ... icals.html

Facilities using bromine as a sanitiser shall keep the DMH levels no greater than 200 milligrams per litre. http://cat1.poolsafety.com.au/uploaddoc ... 202010.pdf

Dimethylhydantoin (DMH) is a disinfection by-product of BCDMH, which has been associated with skin irritation (bromine itch) when the DMH concentration in pool water becomes too high. Pool operators need to maintain DMH below 200 mg/L. http://www.health.nsw.gov.au/resources/ ... g_pool.pdf

Is there any way to test for DMH? I take it that dilution is the only means of lowering it?

The spa gets drained pretty much weekly so I can't see a problem there, but the pool is another story. We drained it in December (due to a fire), but before that it had probably been 5 years since a complete refill (resurfacing). We normally order 50 lbs of bromine about every 3 months, keeping the pool and spa at around 6ppm, normally.

I'll probably continue with bromine in this pool/spa, but now I have a reason to distrust that as well.

There is no poolside test kit that I know of to test for DMH. The only way, other than taking a sample to a special lab, is to calculate the level based on the amount of tablets used. Every 10 pounds added to 24,000 gallons will add 26 ppm of DMH. 50 pounds of tabs will add 130 ppm of DMH. The tabs are about 52 % DMH by weight.
Dilution and reverse osmosis are the only ways to remove DMH. Some areas have a service that will come to you with a commercial grade reverse osmosis setup to clean your pool water. Southern California and Arizona are the only areas that I know have the reverse osmosis service available.

You can use bromine in the indoor pool without using tabs. You just add 8 pounds sodium bromide ( for 24,000 gallons) and then use liquid chlorine as the oxidizer.

 

[chem geek]

The main advantage of the tabs is the regular bromine dosing so is useful in residential spas that are not used every day or two (that's also the advantage of Trichlor tabs for pools). The bromine tabs provide a residual while after spa use one adds an oxidizer to handle the spike in bather load. For commercial/public pools, automatic feeders would be better, such as saltwater chlorine generators (for chlorine) or peristaltic pumps. Usually this is combined with ORP measurement systems to approximate an FC level that is to be maintained. You can still have a bromine pool with a peristaltic pump adding chlorine since the chlorine will oxidize bromide to bromine (assuming you have a bromide bank by initially adding sodium bromide or having used tabs for some time).

Unfortunately, tabs of any sort aren't pure sanitizer so have side effects. Bromine tabs increase DMH. Trichlor tabs increase CYA. Cal-Hypo tabs increase CH.

There are two types of bromine tabs. 1-bromo-3-chloro-5,5-dimethylhydantoin (BCDMH) and 1,3-dibromo-5,5-dimethylhydantoin (DBDMH). In both cases, assuming a bromide bank exists, one produces 2 moles of bromine for every mole of DMH added. So for every 1 ppm Bromine from tabs one gets (128.13 g/mole DMH)/( (2 bromine per tab)*(2 bromine in Br₂)*(79.904 g/mole Br) ) = 0.4 ppm DMH. For every 10 ppm Bromine from tabs, one gets 4 ppm DMH. The standard Water Replacement Interval (WRI) defined in ANSI/APSP-11 is (1/3) x (Spa Volume in U.S. Gallons) / (Number of Bathers per Day) where soak time in a hot (104ºF) tub is probably around 20 minutes. This roughly works out to a cumulative FC from bather load of 270 ppm (about 610 ppm bromine) between water changes. If all bromine came from tabs, then this would be a DMH of over 240 ppm so somewhat over the maximum recommended limit.

 

[AClogston]

Ugh! My General Manager is going to hate my finding this website, but I like knowing this stuff. Thanks guys.

According to the CPO handbook:
"There are two methods of providing hypobromous acid (HOBr) to pools and spas other than elemental bromine. The first is sodium bromide activated by the oxidizer, potassium monopersulfate. This method is called the two-part system, it is limited in use to small volumes of water and is not used for commercial pools The second is a solid form of bromine bound to an organic molecule. This solid is dissolved in a soaking or erosion type feeder to deliver hypobromous acid. Organic bromine compounds are used in commercial pools and spas."

If I used chlorine, like you mentioned, instead of MPS, as in the book, as a two-part system would this still be ruled out for use in commercial pools? And if I use chlorine to oxidize after using sodium bromide, does that bromide bank from the initial 8 lbs. of sodium bromide remain as long as I never completely drain the pool? No matter all the backwashing, fill water, etc? Or does the sodium bromide need to be replenished periodically?

Like I said, the state code mentions no limit on DMH, so we're in no danger there, but I'd like to have the cleanest water I can.

 

[JasonLion]

The bromine bank remains in the water for a time. It will break down very very slowly (years and years) and of course you will lose some by splash out, backwashing, and water replacement. To get rid of it completely you need to drain and refill.

Regulations vary from place to place. I can't think of any reason they would not allow using chlorine to reactivate bromine, but you never know.

 

[AClogston]

OK, here's another newbie-ish question. How do you know when that bromide bank is depleted, and your not just reading the chlorine oxidizer on the test?