Salt Water Generator

[pretzelsb]

Is the salt water system as "germ free" as chlorine?

[Strannik]

Is the salt water system as "germ free" as chlorine?

Salt wtaer generator makes chlorine out of salt water, so it's exactly the same as bleach.

[Aussie Pool Guy]

Is the salt water system as "germ free" as chlorine?

Salt wtaer generator makes chlorine out of salt water, so it's exactly the same as bleach.

try the salt water chlorinator post in fibreglass pools richard explained it well

[jimcagg]

Salt water generators ar Ok but I finally foud the the top gun for keeping your pool clean, germ free and CHEMICAL FREE !!!! Yup Chemical free! I'm an engineer in MA and for years I fought with all kinds of chemicals from chlorine to salt water generators to bromides and etc etc. Finall through some research with an old college professor, I found ionization. Not to belabor the point but you can convert anytime, the system is easily installed, realively inexpensive and fool proof. My pool is absolutely chemical free and it is so pure that it's better than my tap water! It sparkles.

No, I'm not selling the system but I'm so pleased with it, I'm happy to share the results. I haven't spent $20.00 for chemicals in the last 5 months that I have installed the sytem so it will pay for itself in the first year. Last year I chased the darn green water syndrome all year and finally had to pull the plug after spending about $600 or more and chemicals recommended by the 'professionals'.

If you would like more info on the subject you may call or email me anytime, I'll be glad to chat with you.

Jim C 781 233 6848 or Email N20935@aol.com

[Erskin]

Salt water generators ar Ok but I finally foud the the top gun for keeping your pool clean, germ free and CHEMICAL FREE !!!! Yup Chemical free! I'm an engineer in MA and for years I fought with all kinds of chemicals from chlorine to salt water generators to bromides and etc etc. Finall through some research with an old college professor, I found ionization. Not to belabor the point but you can convert anytime, the system is easily installed, realively inexpensive and fool proof. My pool is absolutely chemical free and it is so pure that it's better than my tap water! It sparkles.

No, I'm not selling the system but I'm so pleased with it, I'm happy to share the results. I haven't spent $20.00 for chemicals in the last 5 months that I have installed the sytem so it will pay for itself in the first year. Last year I chased the darn green water syndrome all year and finally had to pull the plug after spending about $600 or more and chemicals recommended by the 'professionals'.

If you would like more info on the subject you may call or email me anytime, I'll be glad to chat with you.

Jim C 781 233 6848 or Email N20935@aol.com

Dont you use some kind of oxidizer? What chemicals did you have to buy?

[deya]

Dont you use some kind of oxidizer? What chemicals did you have to buy?

I too am an copper-silver ionizaton fan. I think it is important to have silver with the ionization because it is more efficient to kill bacteria and virus in a timely manner. One person (Chemguy?) posted on one of these forums that with copper only ionization bacteria can float in the water for up to an hour. I was told that silver did the same thing is a few minutes. I have had my same ionization unit for about 20 years now with no problems.

I just joined today and posted somewhere else about my ionization. I don't want to repeat myself too much but I wanted to answer your question.

I oxidize with chlorine about every 2 weeks, but that depends on how many people and animals have used the pool. I only pour in chlorine and nothing else, so it dissapates in a few hours and then I am chlorine free for the rest of the time. I did use potassium monopersulfate, but started using chlorine because it was cheaper and it seemed to do the trick for oxidizing. I am not sure if the potassium monopersulfate is better. I was hoping to get information here.

Someone also told me about hydrogen peroxide, but at this point I am not sure how to use it. I seem to be fine with the chlorine, since it is only in my pool water for a few hours. I just arrange my swimming time accordingly.

[chem geek]

Copper is better at killing algae and silver is faster at killing bacteria, but even silver does NOT kill bacteria as quickly as chlorine. With Free Chlorine (FC) at around 5% of the Cyanuric Acid (CYA) level, chlorine kills 99% of easy-to-kill (CT 0.04 to 0.08) bacteria in 1-2 minutes. However, it takes silver (in the best case at hot temperatures at concentrations found in spas) at least 10-20 minutes to achieve the same result (it takes copper at least 2-3 times as long as that). Silver can kill "easy" bacteria faster than they can reproduce, but not fast enough to prevent person-to-person transmission. Also, harder-to-kill bacteria, such as Pseudomonas aeruginosa that causes hot tub itch, requires higher chlorine levels and it is not at all clear how long it takes for silver to kill it nor if silver has any effect on biofilms (this bacteria very quickly forms biofilms). Silver is a catalyst so will accelerate the existing oxidation reactions with dissolved oxygen and chlorine (and silver itself can interfere by direct attachment to certain molecular sites), but with chlorine pool studies showed that you still needed 1 ppm FC even when using silver so that you didn't "run out" of chlorine locally.

The Nature2 system which uses silver ions is effective only because it also uses either non-chlorine shock, MPS, or chlorine along with the silver metal ions AND this is only at hot spa temperatures. Silver plus MPS does not kill bacteria fast enough in pools (due to lower temperatures) which is why this combination is not an EPA-approved sanitizer for pools. The table of possible hot tub itch/rash/lung incidents reported mostly on this forum that I compiled here may indicate that metal ions alone may not be sufficient to prevent hot tub itch. The most common cause is too low a sanitizer level with no metal ions, but some incidents were reported even with metal ions being used. Even using Dichlor-only could potentially cause problems after a month or so as the Cyanuric Acid (CYA) level builds up and active chlorine levels drop because of that.

Richard

[Pool Clown]

And it's Chem Geek for the win!

[deya]

Copper is better at killing algae and silver is faster at killing bacteria, but even silver does NOT kill bacteria as quickly as chlorine. With Free Chlorine (FC) at around 5% of the Cyanuric Acid (CYA) level, chlorine kills 99% of easy-to-kill (CT 0.04 to 0.08) bacteria in 1-2 minutes. However, it takes silver (in the best case at hot temperatures at concentrations found in spas) at least 10-20 minutes to achieve the same result (it takes copper at least 2-3 times as long as that). Silver can kill "easy" bacteria faster than they can reproduce, but not fast enough to prevent person-to-person transmission. Also, harder-to-kill bacteria, such as Pseudomonas aeruginosa that causes hot tub itch, requires higher chlorine levels and it is not at all clear how long it takes for silver to kill it nor if silver has any effect on biofilms (this bacteria very quickly forms biofilms). Silver is a catalyst so will accelerate the existing oxidation reactions with dissolved oxygen and chlorine (and silver itself can interfere by direct attachment to certain molecular sites), but with chlorine pool studies showed that you still needed 1 ppm FC even when using silver so that you didn't "run out" of chlorine locally.

The Nature2 system which uses silver ions is effective only because it also uses either non-chlorine shock, MPS, or chlorine along with the silver metal ions AND this is only at hot spa temperatures. Silver plus MPS does not kill bacteria fast enough in pools (due to lower temperatures) which is why this combination is not an EPA-approved sanitizer for pools. The table of possible hot tub itch/rash/lung incidents reported mostly on this forum that I compiled here may indicate that metal ions alone may not be sufficient to prevent hot tub itch. The most common cause is too low a sanitizer level with no metal ions, but some incidents were reported even with metal ions being used. Even using Dichlor-only could potentially cause problems after a month or so as the Cyanuric Acid (CYA) level builds up and active chlorine levels drop because of that.

Richard

I am not sure about who Nature 2 is. The product I use is called Wailani. I use it on my pool and do not own a spa. And if I did I would NEVER sit in a heated chlorinated body of water. The fumes from chlorine are very damaging to the lungs which are even more intense in a heated spa!!! And it is even worse in an enclosed room!!!!

Also isn't Cyanuric Acid a derivative of Cyanide?

Pardon me for cutting and pasteing the rest but I don't have time to post and would be interested to here how you respond the harmful effects of chlorine when combined with the organic matter in the pool.

Pools have to be kept clean to be used safely, but the chlorine used in many pools and inhaled or absorbed through the skin in large amounts has been reported to have some possible bad effects. The International Agency for Research on Cancer has determined that dioxins, furans, and trihalmenthanes (similar in structure to PCBs) can arise when chlorine comes into contact with organic matter such as leaves and dirt, and can cause a possible increased risk of cancer; possible damage to the liver, kidneys, and the nervous system; and possible increased risk of birth defects.[13][14][1]

A study from Belgium's Catholic University of Louvain found that chlorine could be linked to childhood asthma (in 2-3 percent of cases.)[15] Chlorine may also cause skin and eye irritations and longer-term respiratory problems like “swimmer’s asthma.” The US Environmental Protection Agency (EPA) has reports and recommendations regarding chlorine.[16]

Silver is now widely used in hospitals for it's antibacterial properties. Chlorine may be used to clean surfaces, but it is NEVER used on anything that actually comes in contact with any open wounds or orafices.

One bacteria that is resistant to chlorine is legionella, which causes legionnaires disease.

At one time I did do a lot of reasearch on the harmful effects of chlorine. When I posted I never expected a response but I don't mind. It may take me a while to respond but I hope we can keep this dialog open. Maybe we can both learn something!

[chem geek]

I am not sure about who Nature 2 is. The product I use is called Wailani. I use it on my pool and do not own a spa. And if I did I would NEVER sit in a heated chlorinated body of water. The fumes from chlorine are very damaging to the lungs which are even more intense in a heated spa!!! And it is even worse in an enclosed room!!!!

Nature2 (shown here) introduces metal ions (copper, silver, zinc, depending on specific system) to prevent algae and for helping with disinfection. I presume that Wailani you refer to is what is described here. It is essentially the same thing as it is a silver & copper ion system though they also offer a combination with an ozonator.

The amount of chlorine that outgasses is a function of its concentration so depends on the FC/CYA ratio, not just on Free Chlorine (FC) alone. Many hot tub users add chlorine after the soak and soak with low levels of chlorine. This won't prevent person-to-person transmission, but will usually be sufficient for killing introduced bacteria right after the soak. Others soak with chlorine and don't have problems. The levels of chlorine that damage lungs is far higher than found in spas. As for chlorine exposure limits, you can see that here. With 0.05 ppm hypochlorous acid concentration (as occurs with an FC/CYA ratio of 0.1) in the water, the equilibrium concentration of hypochlorous acid in the air is on the order of 1 ppb though at higher spa temperatures it's still less than 10 ppb or 50-100 times less than the limits described by OSHA (technically, these were limits for chlorine gas, not for hypochlorous acid). For chlorine gas, the equilibrium amount in air under these same water conditions is on the order of 3 parts-per-trillion and still less than 30 parts-per-trillion or 16,000 to 33,000 times less than the OSHA limits. Note that these already very low and safe amounts are equilibrium amounts and the concentration in the air above the spa won't even get near that amount except very close to the water surface.

Most people in hot tubs using chlorine don't notice a chlorine smell until the FC/CYA gets above around 0.02-0.05 or so in hot (100-104F) tubs with aeration jets. This is consistent with studies that show the odor detection limit for hypochlorous acid to be around 0.28 ppm in room temperature water and that of monochloramine being 0.65 ppm, dichloramine being 0.1-0.5 ppm, trichloramine being 0.02 ppm (20 ppb). It is the latter trichloramine (aka nitrogen trichloride) that is by far the most irritating and is also the most volatile, but is also controlled and limited by appropriate FC/CYA and pH levels.

Also isn't Cyanuric Acid a derivative of Cyanide?

No. Cyanide is a single carbon and nitrogen connected with a triple bond as shown here. Cyanuric Acid is a hexagon ring of carbon and nitrogen atoms connected with single and double bonds as shown here. Cyanuric Acid can be derived from urea. You can't compare chemical compounds on the basis of similar sounding names.

Pardon me for cutting and pasteing the rest but I don't have time to post and would be interested to here how you respond the harmful effects of chlorine when combined with the organic matter in the pool.

Pools have to be kept clean to be used safely, but the chlorine used in many pools and inhaled or absorbed through the skin in large amounts has been reported to have some possible bad effects. The International Agency for Research on Cancer has determined that dioxins, furans, and trihalmenthanes (similar in structure to PCBs) can arise when chlorine comes into contact with organic matter such as leaves and dirt, and can cause a possible increased risk of cancer; possible damage to the liver, kidneys, and the nervous system; and possible increased risk of birth defects.[13][14][1]

A study from Belgium's Catholic University of Louvain found that chlorine could be linked to childhood asthma (in 2-3 percent of cases.)[15] Chlorine may also cause skin and eye irritations and longer-term respiratory problems like “swimmer’s asthma.” The US Environmental Protection Agency (EPA) has reports and recommendations regarding chlorine.[16]

(By the way, when you are cutting and pasting, you should refer to the source via a link or better yet just post the link. The above appears to have been taken from here.)

Dioxins are only created when certain organics (such as wood fibers) combine with chlorine under very concentrated conditions, such as found in bleaching wood pulp when making paper or in conditions of burning or incineration at specific temperatures. Chlorine is not used very much anymore for bleaching wood pulp though chlorine dioxide is sometimes used and chlorine-free oxygen-based bleaches are more frequently used. Again, you can't compare apples and oranges comparing chlorine used in concentrations for bleaching wood pulp, as well as the very low pH in that process, that is nowhere near that in pools. In a pool with a Free Chlorine (FC) level that is 10% of the Cyanuric Acid (CYA) level, the active chlorine concentration is equivalent to only around 0.1 ppm FC with no CYA and the pH is near 7.5. Ordinary bleach has a chlorine concentration of 60,000 ppm and the (previously) typical chlorine bleaching process using chlorine gas has a very acidic pH below 2.

It is true that there are reports and studies of respiratory problems including asthma associated with chlorine pools, but these are all with INDOOR pools where (most likely) Cyanuric Acid has not been used (air circulation is also worse than outdoor pools and there is no UV since no sunlight). The active chlorine concentrations in such pools are 10-30 times higher than in pools using CYA. This is because CYA binds to most of the active chlorine (hypochlorous acid) so very little of the active compound remains (you can read the scientific paper that definitively determined the chlorine/CYA relationship here). The higher chlorine concentrations can lead to a greater production of disinfection by-products. This is predicted in the breakpoint chlorination models of ammonia which produce higher concentrations of nitrogen trichloride at higher chlorine concentrations (proportional, so 10-30 times in indoor pools). No definitive model of oxidation of urea by chlorine has been confirmed, but it may also produce more nitrogen trichloride at higher chlorine concentrations. Water treatment plants intentionally use lower chlorine levels over a longer period of time to be able to kill bacteria (same CT product) but at lower chlorine concentration to reduce the disinfection by-product quantities.

Nevertheless, if there was an effective disinfectant as chlorine without the side effects, that would be great, but as you'll see below, there isn't anything that effective with a residual in the bulk pool water relatively long-lasting and that can kill fast enough not only to prevent bacterial growth, but also to prevent person-to-person transmission. Bromine and Baqua/biguanide/PHMB are the only other EPA-approved sanitizers, along with chlorine, that can be used standalone. For spas, due to high temperatures, a combination of silver ion and a high enough concentration of non-chlorine shock, MPS, is nearly effective as chlorine, but this is not true at lower temperatures such as found in pools.

Silver is now widely used in hospitals for it's antibacterial properties. Chlorine may be used to clean surfaces, but it is NEVER used on anything that actually comes in contact with any open wounds or orafices.

One bacteria that is resistant to chlorine is legionella, which causes legionnaires disease.

At one time I did do a lot of reasearch on the harmful effects of chlorine. When I posted I never expected a response but I don't mind. It may take me a while to respond but I hope we can keep this dialog open. Maybe we can both learn something!

Silver is fine to use an an anti-bacterial agent when you've got time to kill the bacteria or when it's concentrated so kills faster. The problem is that silver in pools at higher concentrations can stain especially if the pH rises (copper also has this problem). The U.S., Australia, and other countries have looked at using metal ions, including silver, in pools for sanitation, but concluded that by itself it was not sufficient to prevent transmission of disease. So if used at all in commercial/public pool situations, it is used in conjunction with a fast-acting sanitizer such as chlorine.

As for Legionella pneumophila, this link shows that though this bacteria is harder-to-kill than the easy Escherichia coli, it is still killed by chlorine. Instead of a 99% kill in 1 minute with Escherichia coli, it's 40 minutes with Legionella pneumophila which is faster than needed to kill it before it can reproduce and Legionella pneumophila is not transmitted from person-to-person. Note that in this paper the chlorine level was 0.1 ppm which is equivalent to the FC that is 10% of the CYA level I mentioned earlier (e.g. 3 ppm FC with 30 ppm CYA). Legionnaires disease is very serious and Stacey reported getting that from an unsanitary hotel hot tub (as described here), but this was a situation with improper sanitation -- not even silver ions, let alone maintained chlorine.

There is no question that chlorine in some situations is harmful, but in pools when properly dosed it's the most effective disinfectant available. The main problem with chlorine disinfection in pools is that it is ineffective against protozoan oocysts, especially Cryptosporidium. Chlorine dioxide is more effective, but it decomposes too quickly in sunlight to be used regularly, though it can be used for shocking at night (this is not currently done as studies needed for EPA approvals for chlorine dioxide use in pools haven't been done).

If you want to minimize the amount of chlorine you need, you can use a lower FC/CYA ratio, but then you need something else to kill algae since algae is far harder to kill than most bacteria. You can use a supplemental weekly algaecide, such as PolyQuat 60, or use a phosphate remover (you could also use copper, but that can stain, just like silver). For preventing green algae using chlorine alone, a minimum FC of 5% to 7.5% of the CYA level is needed.

Richard

[Strannik]

deya: silver or copper ions are fine when the only people swimming in the pool are you, your wife and kids

if you have other people coming - it's not enough

[chem geek]

It's a spectrum of risk with metal ion use without chlorine being more risky than using chlorine. In the table I compiled with reports of hot tub itch/rash/lung/cough, there were two incidents, this one and this one where Nature2 or Nature2 with an ozonator were being used with little or no chlorine (or MPS). As I note in the table, this is not definitive and way too small a sample and in many cases not confirmed by doctors.

Pseudomonas aeruginosa forms biofilms quite readily so if not killed when free-floating (planktonic) it may be that silver ion is somewhat less effective than chlorine in that situation. The larger number of hot tub itch/rash/lung reports after Dichlor is used for more than 1-2 months may be due to the buildup of CYA which reduces the active chlorine level (at the same FC). This was one reason why I recommended using Dichlor initially and then switching to bleach so that the active chlorine concentration would remain constant and not decrease over time. Pseudomonas is not something you typically get from other people since it's fairly ubiquitous. The problem is when it finds an environment such as warm water in which it can grow to numbers where it can then overwhelm normal immune defenses. It's not like the protozoan cysts (Giardia, Cryptosporidium) or bacteria (E. coli, Shigella) shed in diarrhea (or fecal matter) or viruses shed in mucous.

That said, Pseudomonas is much more common in spas than in pools (the bacteria prefers hotter water temperatures). So the risk (for this bacteria) is lower in a pool. Also, to prevent algae, copper is needed (or another algaecide or phosphate remover). However, to have a high enough level of silver for killing bacteria and copper for preventing algae in a pool, you have to carefully watch the pH since plaster will stain from silver and copper oxides at higher pH. Also, people with blond hair can get a greenish tint from the copper.

At a minimum, use of metal ions alone will require addition of some sort of oxidizer (non-chlorine shock, ozonator, strong enzymes and enough oxygen) to eliminate bather waste, otherwise the pool will build up ammonia and urea.

There is no question that using metal ions is far better than using nothing at all, but no one should believe that it is as effective, by itself, as even low doses of chlorine (i.e. FC that is about 10% of the CYA level, so equivalent to around 0.1 ppm FC with no CYA).

Richard

[lonestar23]

just remember:

a tablespoon of fecal matter per swimmer. avoid public hottubs.

[chem geek]

See also this post with the EPA requiring Nature2 to label properly saying that chlorine is required.

[PoolFacts]

See also this post with the EPA requiring Nature2 to label properly saying that chlorine is required.

COPPER IONIZATION--I have some familarity with 2 copper ionizers that purport to do away with chlorine. ChlorineFreeUSA and EcoSmarte. What do you think of these kind of devices as your primary sanitation device in a pool?

CHLORINE AND ASTHMA CONNECTION--http://www.nhs.uk/news/2009/09September/Pages/SwimmingAsthmaRisk.aspx This is a link to an article that discusses the study that reported the connection between chlorine and asthma in 2009 and reported the connection as "signifigant". What do some of the chemical gurus think of this connection. I have been telling customers that the weight of current studies is that they are "suggestive" of a link but not conclusive. Based on this possible link, I always push a Frog or Nature II to lessen the amount of chlorine in the pool. Am I being too paranoid about this issue?

[chem geek]

Using a copper ionizer alone won't provide any oxidation of bather waste so I presume you mean using ozone or non-chlorine shock to handle that, right? Copper takes around 40 minutes for a 99% kill of typical bacteria that it takes chlorine about 1-2 minutes to kill (at an FC that is around 10% of the CYA level). Metal ions aren't very good at inactivating viruses. So it's a spectrum of risk and clearly not fast enough to prevent person-to-person transmission (or other fecal-to-oral route transmission) though might be enough to prevent uncontrolled bacterial growth in some cases. Silver ion would kill about twice as fast; copper is better at killing algae. These systems would not be allowed in commercial/public pools, but there are no laws forcing you to sanitize your own residential pool any way you like. If you get ill, you can't sue the government.

As for the Dr. Albert Bernard asthma studies, I write about those here. If you want to lessen the amount of chlorine in the pool, then you can just use a regular weekly algaecide such as PolyQuat 60 since it is the prevention of algae growth that requires more chlorine. Copper will prevent algae as well, but can stain so would be a particularly bad choice in plaster pools. You could use 50 ppm Borates to inhibit algae or use (expensive) phosphate removers, but none of these will stop algae growth, though they should slow it down enough for you to lower chlorine levels somewhat -- but probably not much less than half (so perhaps down to an FC that is 2%-3% of the CYA level). If you go much lower than that then you slow down oxidation of bather waste so might need supplemental oxidation.

[PoolFacts]

Using a copper ionizer alone won't provide any oxidation of bather waste so I presume you mean using ozone or non-chlorine shock to handle that, right? Copper takes around 40 minutes for a 99% kill of typical bacteria that it takes chlorine about 1-2 minutes to kill (at an FC that is around 10% of the CYA level). Metal ions aren't very good at inactivating viruses. So it's a spectrum of risk and clearly not fast enough to prevent person-to-person transmission (or other fecal-to-oral route transmission) though might be enough to prevent uncontrolled bacterial growth in some cases. Silver ion would kill about twice as fast; copper is better at killing algae. These systems would not be allowed in commercial/public pools, but there are no laws forcing you to sanitize your own residential pool any way you like. If you get ill, you can't sue the government.

As for the Dr. Albert Bernard asthma studies, I write about those here. If you want to lessen the amount of chlorine in the pool, then you can just use a regular weekly algaecide such as PolyQuat 60 since it is the prevention of algae growth that requires more chlorine. Copper will prevent algae as well, but can stain so would be a particularly bad choice in plaster pools. You could use 50 ppm Borates to inhibit algae or use (expensive) phosphate removers, but none of these will stop algae growth, though they should slow it down enough for you to lower chlorine levels somewhat -- but probably not much less than half (so perhaps down to an FC that is 2%-3% of the CYA level). If you go much lower than that then you slow down oxidation of bather waste so might need supplemental oxidation.

Thanks--I really liked your discussion of the chlorine/asthma issue. Another question about the copper ionizers, some like ChlorineFreeUSA (http://www.chlorinefreeusa.com/howitworks.htm) purport to create oxygen as an oxidizer which they say is "5 times more powerful than sodium hypochlorite" which then burns up the "bacterial and viral contaminants". Copper ions (no silver) are then used to control algae and fungus. This all sounds good but I wonder if you see any big holes in this approach??

[chem geek]

The main problem with any system that works in the filtration system, be it oxygen (hydroxyl radical), ozone, UV, etc. is that it does not provide a residual sanitizer in the bulk pool water itself so will not handle the killing of pathogens that could stick on pool walls in biofilms or otherwise do not get quickly circulated through their unit. At least with their system, the copper ions provide some protection in the bulk pool water, though that's mostly against algae growth (though it does slowly kill some other pathogens). They don't have any copper ion measurement control so they require weekly copper ion testing to make sure the level doesn't climb too high and cause staining or get too low which could allow algae to grow.

Since this uses copper ions, it has similar issues to what I described in my earlier post. It won't kill quickly enough to prevent person-to-person transmission so it won't be allowed in commercial/public pools without an EPA-approved disinfectant such as chlorine, bromine, Baqua/biguanide/PHMB. Unfortunately, the strong oxidation systems will tend to breakdown chlorine (to chlorate for ozone, to chloride for UV; unsure with hydroxyl radical). As for a residential pool, it at least has something in the bulk pool water, albeit a slow killer, and it has a strong oxidizer in the filtration system (though unclear how much of the strong oxidizer is produced). So it's a risk some residential pool owner's would be willing to take in order to be halogen-free. Note that if there is some chloride in the water, then some small amount of chlorine may be produced anyway though I presume they have made their system primarily produce oxygen. It is unclear how many oxygen radicals (such as hydroxyl radical) are produced so it is unclear if the system provides enough oxidation to handle the sweat and urine from higher bather loads or from organic contaminants getting into the pool. Some of these electrolysis systems are just standard splitting of water into oxygen and hydrogen gases and because they theoretically produce some oxygen radicals due to higher overvoltages applied, they make that claim but the amount isn't enough for decent oxidation. Without independent lab studies or other tests showing how long it takes to clear a pool of contaminants (sweat, urine, lotions, etc.) it's hard to know if the system is any good.