SWG vs Ozonator vs UV?

[bk406]

chlorine byproducts as carcinogens.

I'm not sure there's good evidence of it. But, the key word is BYPRODUCTS. In a properly chlorinated pool, those byproducts, or combined chlorines, are non exisitent. My 6 month old and 3 yo goes in my pool with 6 ppm free chlorine. My CYA level is close to 50. This really is the equivelent of ~0.2 ppm active chlorine. Not a lot (chemgeek can confirm or solidify those numbers). The FC/CYA is not ever taken into acount in these studies, I dont think. And..I have never had CC over 1 ppm, ever.

Believe what you like, but swimming in a properly chlorinated pool is more dangerous than anything else.

 

[henry89056]

Hey Beez -

Yea, I understand what you are suggestion - that you can achieve a lower overall FC # with an accordingly lower CYA level. But this doesn't speak to maintaining that FC ratio, which would seem to become correspondingly more expensive the more chlorine is consumed by sanitation/oxidation (and via UV-A, or sunlight).

I didn't want to confuse the original question with another factor I have in the back of my head, which is: I would also like to decrease chlorine costs (or lower the amount of chlorine used over time) - assuming we use an in-line feeder and not a SWG.

Maybe achievable, maybe not. But that's why I'm attempting to educate myself to gather representative user experiences and data.

 

[dmanb2b]

I'll let Jason answer and and this is just my opinion, so take it for what it is worth, but swimming pools have been around a while and although some may be writing articles about chlorine and it's harmful effects, I highly doubt the levels we maintain in our water is anymore harmful that sunbathing next to the pool, inhaling the air in our cars while sitting in traffic, or for those with finished basements who are inhaling radon gas...etc.

My point, when someone tells me a tried and proven sanitation method is deemed unsafe, I'll stop using it.

The fact that the OP is researching this topic with the manufacturers that make the UV/mineral equipment, will prove nothing. Of course they will tell you their devices work.

 

[henry89056]

dmanb2b - I understand what you are saying, but this also sounds a lot like tobacco companies lobbying that cigarettes are safe. For dozens of years that was the prevailing thought. But I don't think people believe that is true any longer.

I simply see little harm in investigating alternatives / options.

 

[teapot]

chlorine byproducts as carcinogens.

Believe what you like, but swimming in a properly chlorinated pool is more dangerous than anything else.

I am sure that is Not what you mean?

Most references to carcinogens in chlorinated pools actually come from pedlers of "alternative" sanitisers and the paranoid non science.

I have a customer with UV who suffers with algae every August and he insists on using hydrogen peroxide not chlorine. maintaining the chlorine level as sugested on this forum will produce excellent results and no danger of waisting money on UV or producing more toxic substances but in the end its your money to do with as you wish.

Dirk, just read your post, Are the UV companies telling you about the Cyanagen gas reports from chlorinated pools??
http://www.drydenaqua.com/afm/appli...d crypto/uvc_irradiation_and_cryptosporid.htm

 

[henry89056]

The fact that the OP is researching this topic with the manufacturers that make the UV/mineral equipment, will prove nothing. Of course they will tell you their devices work.

Just to address: I don't think there is any debate that UV-C technologies are proven to work. They have been used extensively in varying capacities throughout the world as a germicide. I think understanding their practical impact/effectiveness in outdoor pool systems lacks adequate data (for me anyway).

I spoke to a Siemens UV engineer this morning regarding their device line and specifically their PVC line for pool sanitation. It isn't make-believe technology; Siemens sells their systems worldwide. http://www.water.siemens.com/en/pro...n/ultraviolet_disinfection/Pages/default.aspx

 

[frustratedpoolmom]

Dirk - I think it's great that you are doing your homework before you buy instead of falling for some pitch etc.

Your statement "I think understanding their practical impact/effectiveness in outdoor pool systems lacks adequate data (for me anyway)." sums it up pretty well. add to that residential pools...

I'm just not sure the added expense is worth it for a residential pool, and by continuing your research I think you'll find the proper testing techniques and methods we advocate here minimize the amount of chlorine needed, and that much of the "issues" attributed to chlorine use are really the result of the byproducts. I myself have run my pool since 2007 using the TFP methods and never had a trace of CCs present.

Keep up the good research, in the end the final decision will by yours so you want to be happy with whatever you decide.

 

[henry89056]

Dirk, just read your post, Are the UV companies telling you about the Cyanagen gas reports from chlorinated pools??
http://www.drydenaqua.com/afm/appli...d crypto/uvc_irradiation_and_cryptosporid.htm

I think I need to better understand the context of this - because the article is very generic. A quote from that article: The problems relate to all chlorinated swimming pools exposed to UVc irradiation from sun-light, either out-door pools or indoor pools with large windows and from UV irradiation systems, especially medium pressure units.

My understanding is that UV-C lamps fall into a number of categories. Many indoor, municipal pools use so-called "medium pressure" lamps that operate across a broader section within the UV-C spectrum. These lamps are purportedly more effective at eliminating a broad-spectrum of chloramines, desirable to reduce off-gassing in indoor pools.

The common residential pool UV-C lamps are "low pressure" lamps orienting specifically on UV243 (UV243.7), which correlates to highly a effective germicide.

Also, I am unclear on the article's assertion of these issues resulting from UV-C irradiation from sunlight. About 98.7% of the sunlight that reaches earth is UV-A. So, if irradiation from UV-C is a problem from sunlight, then everyone using chlorine should be concerned about this phenomena - not just pools using UV-C inline sanitation. The article does suggest it could be a concentration issue, but again, per my discussion with Siemens earlier today, the medium pressure lamps typically found in large pool complexes operate entirely differently than the low-pressure lamps in residential drinking water or pool applications.

Will continue to research ...

 

[Beez]

Hey Beez -

Yea, I understand what you are suggestion - that you can achieve a lower overall FC # with an accordingly lower CYA level. But this doesn't speak to maintaining that FC ratio, which would seem to become correspondingly more expensive the more chlorine is consumed by sanitation/oxidation (and via UV-A, or sunlight).

I didn't want to confuse the original question with another factor I have in the back of my head, which is: I would also like to decrease chlorine costs (or lower the amount of chlorine used over time) - assuming we use an in-line feeder and not a SWG.

Maybe achievable, maybe not. But that's why I'm attempting to educate myself to gather representative user experiences and data.

--Dirk

This comment just shows that you haven't done enough research on this site. By all means, continue with your research, but do yourself a favor and dig in a little bit here. One of the regular contributors here, chemgeek, has written extensively on the relationship of CYA to chlorine.

Every goal you have listed is addressed by the "BBB" method that is advocated on this website. Every concern you have voiced has also been discussed here and is available to you in the archives.

Good luck to you,
Dave

 

[teapot]

Dirk, there is considerable information via the world health organization re the problems you are high lighting with byproducts and sun light so I believe you are partially correct in your assumptions although sun light UV also destroys some of the byproducts which is why in Europe steps are being taken to reduce the use of chlorine where possible.

I have some information on low pressure UV and the fact it does damage to the cell DNA of bacteria etc, however as it has only a narrow band frequency the bacteria are able to re-generate itself (repair) and then carry on reproducing, so a high pressure wide frequency is really the way to go although I would still not bother for a domestic setup.

If you are really looking at a system that removes everything in a carefully controlled way there is a German company doing just that, I do not have their information any more but it was around 25000 euros for the system which surpassed the German DIN standard easily

 

[henry89056]

Dave - yea, I am reading a fair amount on this site and others. My comment on 'achievability' was more oriented toward UV-C, not traditional sanitation methods.

I am confident traditional methods will adequately sanitize the pool - well, perhaps with the exception of certain chlorine-resistant viral strains. I'm less confident that UV-C can do this without a traditional chlorination scheme.

Anyway ...

 

[JasonLion]

I'm less confident that UV-C can do this without a traditional chlorination scheme.

UV without chlorine (or bromine or baquacil) won't do much of anything against bacteria or algae, though it will kill viruses (quite slowly however). UV can only kill things that go through the UV cell. Chlorine has a 99% kill rate that is measured in seconds or minutes, depending on what you are trying to kill, which is working on everything throughout the entire pool. Even if the UV lamp has a 100% kill rate, it will be an average of four to ten hours before any given bit of water goes through the UV cell. In the mean time the bacteria and algae that are not currently in the UV cell will be replicating and spreading throughout the pool.

 

[henry89056]

UV without chlorine (or bromine or baquacil) won't do much of anything against bacteria or algae

Again, based on what evidence? From what I've read, the original use of UV (in medical facilities and sterile environs) was specifically developed to neutralize bacteria. As a technology, UV has been available since the turn-of-last-century. This is well documented on sites ranging from Wikipedia to specific application providers and facilities. So, I don't buy that it isn't an effective solution in that regard.

However, if what you are saying is that "UV without effective pool circulation and turn-over won't do much of anything against bacteria or algae", then that might be a truer statement. Without context, however, I do not think it is factual based on the original purpose of UV as a generally accepted germicide technology - pool application notwithstanding.

One thing is most certainly true: you have to pass the water over the lamp for it to be effective. So, a well designed water circulation scheme would be mandatory in electing a setup like this. Doesn't hurt in a conventional setup either.

 

[Beez]

I'm less confident that UV-C can do this without a traditional chlorination scheme.

Precisely. UV and ozone sound intriguing until you realize that you will need the same amount of chlorine in your pool whether you have the adjunctive systems or not. :idea:

 

[bk406]

chlorine byproducts as carcinogens.

I'm not sure there's good evidence of it. But, the key word is BYPRODUCTS. In a properly chlorinated pool, those byproducts, or combined chlorines, are non exisitent. My 6 month old and 3 yo goes in my pool with 6 ppm free chlorine. My CYA level is close to 50. This really is the equivelent of ~0.2 ppm active chlorine. Not a lot (chemgeek can confirm or solidify those numbers). The FC/CYA is not ever taken into acount in these studies, I dont think. And..I have never had CC over 1 ppm, ever.

Believe what you like, but swimming in a properly chlorinated pool is more dangerous than anything else.

OOPPPSSS!!!

swimming in a properly chlorinated pool is NOT ANY more dangerous than anything else

 

[chem geek]

Dirk,

[EDIT] I corrected some numbers -- was off by a factor of 10. Note that there is very little active chlorine in a pool with CYA. Fortunately, it takes a very low level to kill pathogens and prevent algae growth. [END-EDIT]

There are a lot of sources for info on the chlorine/CYA relationship and actual disinfection by-products, but you can start with the chlorine/CYA section (and the CYA and Indoor Pools and Any Spas section) in this thread. Basically, at the minimum FC that is 7.5% of the CYA level recommended on this forum to prevent algae growth in manually dosed pools, this is equivalent to around 0.07 ppm FC with no CYA. For an SWG pool with an FC that is 5% of the CYA level, this is equivalent to 0.05 ppm FC with non CYA. "Equivalent" means that it has the same amount of active chlorine -- hypochlorous acid. Most of the chlorine is bound to CYA and almost inactive. CYA does not absorb through the skin (see here) so chlorine bound to CYA is also very unlikely to be absorbed through the skin.

Disinfection by-products are real, but it is high bather load pools, such as commercial/public pools, where they are at a level that would start to be of concern, especially for indoor pools that typically aren't using CYA and don't have great ventilation (almost all of the studies showing health problems with pools are with indoor commercial/public pools). Residential pools are a whole different category since there is very little to oxidize in the pool. Most of the chlorine usage is due to breakdown from the UV in sunlight which just results in chloride salt.

Richard

 

[Strannik]

One thing is most certainly true: you have to pass the water over the lamp for it to be effective. So, a well designed water circulation scheme would be mandatory in electing a setup like this. Doesn't hurt in a conventional setup either.

--Dirk

a well designed circulation scheme in this case would be a second pool in which no one swims so no bacteria is introduced, and water pumping from one pool to another through a UV lamp and then overflowing back into first pool.

but then you cannot swim in any of the pools because first one will be untreated and you will contaminate the second, so it kinda defies the point of having a swimming pool

 

[JasonLion]

Again, based on what evidence?

UV does absolutely nothing unless the water passes through the cell. A well designed pool with a larger than average pump will take 6 hours to pump the same number of gallons that are in the pool through the pump/UV cell. But not all of the water in the pool will actually go through the pump in that amount of time. Some of the water goes through twice, some of it doesn't go through at all. Meanwhile, the algae that hasn't gone through the pump yet is growing and spreading. An aggressive strain of algae can double in population in 3 hours. The algae wins that race during the day, and loses at night. But even if you run the pump 24 hours a day, you will never kill all the algae, too much water fails to go through the pump/UV cell.

If you built a system that did a turnover in 30 minutes, which would take 12 large pumps and 12 large UV cells, you could get ahead of the algae and effectively kill it all. But even if you did that, you wouldn't be anywhere near the kill rates required by the EPA to certify something as a swimming pool sanitizer. That huge setup would get a 99% kill rate in several hours, while the chlorine levels we recommend are giving you a 99% kill rate in a minute or two.

UV isn't even in the same ball park with chlorine as a swimming pool sanitizer. It is orders of magnitude worse, not even worth thinking about. You keep talking about how UV works in medical, or waste treatment, or other situations where you can guarantee that everything you care about passed through the UV cell before you use it. But in a swimming pool you can't guarantee that, you can't even come close to pretending to approximate that.

 

[chem geek]

[EDIT] I wrote this as Jason was responding. Similar info, but some details on number of turnovers and amount of water circulated. [END-EDIT]

UV without chlorine (or bromine or baquacil) won't do much of anything against bacteria or algae

Again, based on what evidence?

Dirk,

Jason is saying that UV without a residual fast-acting sanitizer in the bulk pool water will do nothing for bacteria and algae in that water until it circulates through the UV system. One turnover of water only circulates 63% of the water (some of the water goes through twice, some three times, etc. and 37% doesn't go through at all). It takes 4.6 turnovers to get 99% of the water through the UV system. Furthermore, any biofilms stuck on pool surfaces don't ever get through the UV system. Also, any bacteria, viruses, or other pathogens in fecal matter or bodily fluids can pass from one person to another without going through the UV system. It is for all of these reasons that a residual fast-acting sanitizer is used in pools and spas.

UV, ozone, etc. are SUPPLEMENTAL systems for oxidation and sanitation; they are NOT primary systems.

Richard

 

[chem geek]

Dirk, just read your post, Are the UV companies telling you about the Cyanagen gas reports from chlorinated pools??
http://www.drydenaqua.com/afm/appli...d crypto/uvc_irradiation_and_cryptosporid.htm

There is conflicting information out there. This EPA report would indicate that UV did not create nor change the rate of formation of DPBs. Note that this report is with regard to disinfecting drinking water.