Healthy ??? PHMB or silver for a baby pool

[PPaul]

I'm looking for a safe sanitization without DBP for my baby's pool.
I have read that chlorine and bromine have a lot of DBP and the skin of a child is very permeable at chloroform.
I have read that Uv and O3 can make DBP too (with a little bit of chlorine).
So what do you know about the use of PHMB with h2o2; or Silver with H2o2.
thanks

 

[duraleigh]

Welcome to the forum. :lol:. The water you drink has chlorine and is perfectly safe....millions have tried it.

I am not sure what some of the items are that you have posted but chlorine is, by far, the simplest way you can take care of a small pool.

 

[Richard320]

You probably bathe your child in water that has more (for want of a better term) reactive chlorine than a balanced swimming pool. Tap water is unstabilized - zero CYA - so whatever Sodium Hypochlorite is in it is all reactive. It might be too heady, but this thread has some charts that show the difference. pool-water-chemistry-t628.html

My nephews take swimming lessons/ drownproofing in a public pool that uses chlorine. No complaints that I'm aware of, nor were there any complaints last summer after they used my pool. Actually, no one has ever complained about dry skin or rashes after using my pool...

 

[chem geek]

Chloroform is a trihalomethane (THM) and is a disinfection by-product when using chlorine, but it is the least problematic of all the THMs. Though it can be absorbed through the skin and inhaled in breath, it is also exhaled and excreted and most importantly it is not cancer-causing or mutagenic until it reaches very high cytotoxic levels far far higher than found in even the worst-managed pool or spa (technical details in this post). The information you have been reading about chloroform is old and inaccurate and are most likely on websites with a financial interest in selling "alternative disinfection" products. The THMs of concern are the brominated ones so when you have a choice, you could use chlorine instead of bromine and can see if your fill water content is low in bromide.

If you follow the principles on this forum in terms of chlorine maintenance, then the active chlorine level will be very low due to the use of Cyanuric Acid (CYA) in the pool that significantly lowers chlorine's strength to the equivalent of around 0.1 ppm Free Chlorine (FC) with no CYA. This reduces the rate of creation of disinfection by-products as well as the rate of oxidation of swimsuits, skin and hair. Also note that the amount of disinfection by-produts is generally a function of bather-load and that this is very low in residential pools. Finally, if the pool is outdoors exposed to the UV in sunlight, then the breakdown of chlorine produces hydroxyl radicals which are very powerful oxidizers -- ozone and hydrogen peroxide both likewise break down to hydroxyl radicals though they obviously don't form chlorinated disinfection by-products.

If you wanted to use the lowest possible chlorine level, then you could use an algaecide such as Polyquat 60 to control algae growth and then have the chlorine level be lower than needed to kill algae, so could have an FC that is only 2-3% of the CYA level so roughly equivalent to 0.02-0.03 ppm FC with no CYA. A similar alternative to control algae, but that can get expensive, is a phosphate remover.

Nevertheless, if you want an EPA-approved non-halogen (no chlorine, no bromine) system for the pool, then PHMB would be your only alternative, but it is expensive and has problems over time, though the first year or two will generally be OK.

 

[PPaul]

First, many thanks for yours answers and your links (very interesting).

- Low FC (2-3% of the CYA) seems to be a good solution with polyQAC. (or, with phosphate remover if i see [phosphate]>1ppm).

First I put CYA and then use Bleach:?: .... And Drain when a fecal insident occurs and balance again
The pool is small and outdoor. So i think the CYA will help me to mantain the pH.
And shock if i see CC > 0,4 with breakpoint calculation or more often with MPS (risk to increase algae nutrients :?: ).

I´m looking for the better way. Here in Spain the "Spanish Pediatric Association" don't recommend swimming in pool for the babies younger than 2 years. and my baby spend many hours every day with her mother into the pool.

- I have read nothing about effects from exposure of PHMB ? do you think it's worst than low level of chlorine ? Do you think PolyQac is safer than a low amount of Copper or Silver ?

(sorry for my spanglish)
Thanks

 

[JasonLion]

Thinking about phosphates is a waste of time and money. As long as you maintain the correct FC levels phosphates make no difference at all.

CYA helps you maintain the FC level in sunlight. TA helps you maintain the PH (up to a point, too high and the PH starts drifting up).

If you are measuring CC by steps of 0.2, then you should shock when CC is 0.4 or higher. However, measuring either FC or CC by steps of 0.2 is not important and wastes reagent. When measuring CC by steps of 0.5 you should shock when CC is 1.0 or higher. Breakpoint calculations are all wrong, a myth really, based on a fairly complex misunderstanding. Follow the shocking your pool procedure described in Pool School.

 

[PPaul]

I was wrong with the breakpoint calculation, thanks.
I use a spectrophotometer with DPD to measure the FC and CC once a week.
And because i don't want to waste time and DPD powder, twice a day FC with an OTO simple kit.
I always put the TA into 80-130 ppm CaCO3 (I use Hach digital titrator) ; nevertheless without CYA i have ever seen : when i put bleach, the pH raise, and when chlorine desapearse, the pH drops.
I don't know if i need to shock. If it is better o worste. if it reduces or creates more bad DBPs (i don't talk about chloramines)... :?
Many thanks.

 

[chem geek]

The DPD test will limited in the FC level it can measure accurately. If you shock to a high level, especially above 10 ppm, it won't be able to measure it. That's why we recommend the FAS-DPD test for chlorine.

A TA above 80 ppm is probably too high when using a hypochlorite source of chlorine. Yes, when you add bleach the pH will rise and when the chlorine gets used up the pH will drop, but also realize that at higher FC (especially above 10 ppm) the pH test can be artificially high. Also, if you don't have any CYA in the water at all, then the chlorine will be too strong and by far the worst thing you can do if you are worried about DBPs and irritation of sensitive baby skin. You really need to put in CYA and manage your FC/CYA level.

If you properly manage the chlorine and CYA levels, then you should not need to shock the water, but with a baby if there's a fecal accident then you may need to raise the chlorine level depending on how much fecal matter was introduced. What size of pool are you talking about?

 

[PPaul]

Thanks for the advise, the FAS-DPD can be very usefull.
I'm going to buy CYA and i will put it directly without the use of trichlorine tablet to raise CYA.
I think : I could put 30 ppm (More could increase the risk that the melamine of toys and plastering accessories reacts with CYA?).
The pool is small cylinder intex 15 ft x 36 in ; 2,822 Gal (10,681 L). I drain 50 % once a week but the next day they can't use the pool because the water is cold.
I see in your table : if CYA=30 ppm and FC=1 ppm, the concentration of HClO = 0,013 ppm (at pH 7,5).
So with poliQAC ; if I maintain 1 ppm during the day, it could be fine.
Many Thanks.

 

[chem geek]

I wouldn't worry about the melamine since it's in solid (polymer) form so if it were to react with CYA at all, then there would simply be a one molecule thick film of CYA on the melamine surface which is not a problem at all.

If the pool is exposed to sunlight, then a low 30 ppm CYA is going to have the chlorine drop quite a lot. If I were you, I'd go up higher in CYA. If you wanted to prevent algae growth and keep the FC low, then use some Polyquat 60. So 2 ppm FC with 80 ppm CYA would be a very low active level of chlorine equivalent to around 0.025 ppm FC with no CYA. Also note that with a small volume of pool water, your chlorine usage from bather load could be high so 2 ppm might not last that long from reacting with bather waste. So you might need to go higher. Just see how things go. The CYA is your real savior here since chlorine bound to CYA is far less reactive (by a factor of around 150) and has virtually no skin absorption.

 

[Speedo]

I'm not going to tell you that any method is wrong. But, I would much rather target the proper (normal) levels and not have to worry that the water is dirty because of a lack of sanitizer (chlorine).

 

[JohnN]

I'm interested in why you drain 50% of the pool once a week. What do you do this for?

 

[Speedo]

I'm interested in why you drain 50% of the pool once a week. What do you do this for?

The proper balance would make this unnecessary. I'm assuming it's done to keep the water fresh (and clean)...?

I'm wondering the same thing.

 

[PPaul]

Chem Geek you are right, this pool is like a spa. It's small and have many bather waste.
If I have understood correctly, if I put more CYA, I can increase the masse of chlorine in the pool. = more chlorine to oxidize more material :?: . and chlorine is less reactive...Great. Is it really like that?

I drain the pool because I'm afraid of the effects of DBPs. And I don't know, how DBPs could be reduced. So I drain 50 % weekly (= 5-10 % daily. Is what the law says for Public Swimming Pools in spain).

Of course I'm afraid of a bad desinfecion and I don't want organic material in my baby's pool. And, I don't want to chose between a gastroenteritis tomorrow and a Scoliosis in 15 years.

Thanks for your help.

 

[chem geek]

Yeah, it's really like that because CYA is a hypochlorous acid (chlorine) buffer. The amount of active chlorine, so therefore chlorine's strength, is roughly proportional to the FC/CYA ratio so if you keep the same ratio then you keep the same chlorine strength. So if you increase both FC and CYA proportionately, then you increase the amount of FC that is the chlorine capacity so that you don't run out. So 2 ppm FC with 50 ppm CYA is the same strength as 4 ppm FC with 100 ppm CYA but you've got twice the chlorine capacity. Note that this ratio requires use of Polyquat 60 algaecide to prevent algae growth. Otherwise, you need the FC to be at least 7.5% of the CYA level (see Chlorine / CYA Chart).

Just note that while the chlorine strength (active chlorine level based on FC/CYA ratio) is what determines the rate of creation of disinfection by-products and the oxidation rate of swimsuits, skin and hair as well as bather waste, the FC or chlorine capacity does have an effect if you drink the water. So if you expect these babies to be gulping down lots of water (something you should avoid regardless of the chlorine level since there a lot of junk in the water you don't want swallowed in quantity) then a lower FC would be better. Just keep in mind that the EPA drinking water limit is 4 ppm FC and they took that into account even for babies drinking water, though obviously not 2 quarts per day as for adults. I would expect/hope that these babies are not on their own so can readily be kept with their heads enough out of the water so that they don't gulp or certainly do not swallow. From this video it seems that perhaps they can learn not to gulp down underwater though that wasn't a skill I learned until much later in life!

As for dilution rates, it's normally specified in Europe as 30 liters (about 8 gallons) of water per bather per day. They don't say it, but it's really per bather-hour. It's not a percentage of the total pool water volume because larger pools automatically dilute whatever is introduced by one bather. We normally don't worry about that for residential pools, but yours is smaller and more like a spa that would get drain/replace every so often. Chlorine will disinfect the water so if your concern is for diluting out organic precursors and disinfection by-products, then that's fine -- probably not necessary, but not a problem if you do it. The other way to handle this is the DIN 19643 approach of using coagulants and filtration along with activated carbon and optional ozonation, but that's all obviously expensive and complicated. Water dilution is a much easier approach.

 

[PPaul]

Thanks,
Ozone and activated carbon will be the best way. I saw this process in drinking water treatments plants years ago.
I would like ... but... not enough money.
And what do you think about PHMB, it's safer ??? and If i have problems ... -> I throw away the pool.
Many Thanks and sorry for my english.

 

[chem geek]

PHMB does not produce chlorinated disinfection by-products so in that sense it's safer, though there's the devil you know (chlorine) and the devil you don't (PHMB) since PHMB hasn't been used and tested nearly as extensively (it's been around, but chlorine has been studied a lot more due to its widespread use in drinking water disinfection). Nevertheless, it's technically probably safer, but of course more expensive and can lead to problems of white water mold, though as you point out you can always change the water completely in your situation. The oxidizer in a PHMB system is hydrogen peroxide. You might have more trouble keeping the water clear with that system though that probably depends on how diligent you are at using enough oxidizer regularly.

Just keep in mind that if you've got bromide in your water, then with any oxidizer (including hydrogen peroxide) you'll get some bromine, albeit briefly (since hydrogen peroxide can reduce it back to bromide) so can get some brominated disinfection by-products. For typical tap water, however, it's probably very low.

 

[PPaul]

I find all yours answers very useful. Now, I have more important informations to make a choice.
I will study the subforum Baquacil to learn a lot. And I'm going to look at the prices of the products.
I think that is a pity, that I do not find this website before. The others forums and are still light years away, Thanks.