Why no ozone? For LOTS of good reasons!
Quote:
Originally Posted by MarkTilley
I'm really surprised there isn't any discussion on this site about ozone generators.
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Our condo is considering replacing the chlorine system in our 36,000 gal. indoor pool with an alternative sanitizer. The pool is not heavily used on weekdays (we have 450 suites) but often has 10-15 swimmers on the weekends. There's also a 1,000 gal. spa.
Sometimes, the absence of discussion is an example of following Grandma's rule, "If you can't say something nice, try not to say anything at all." :)
But, sometimes, it's necessary to get real. It always amazes me how people can be accustomed to hearing, on the one hand, that there are smog problems today, because the "ozone levels are high", and then, on the other hand, get all excited about 'natural' ozone in pools.:confused:
The 'real' fact about ozone is that, for residential outdoor pools, the promotion of ozone is mostly hype and hot air . . . and the pursuit of more $$$ for a couple of manufacturers.:mad:
It *is* possible to use ozone to produce truly outstanding water quality. But the technology to do it with (corona discharge generators) is neither new nor misunderstood. What it is, is complex, expensive, and dangerous. It's used very, very effectively in a number of indoor commercial pools in Europe, mostly in Germany. But, the system used is very expensive, and requires continuous on-site expert supervision.
The reasons why ozone is so difficult and expensive are twofold, and very simple.
First, ozone and chlorine mutually destroy each other, when effective levels of both are present.
Second, ozone is more toxic than chlorine, and less soluble.
Effective levels of ozone can NOT be allowed to reach the pool, because unlike chlorine, the ozone tends NOT to stay in the water. Consequently, effective ozonation systems require a detention chamber, and then a stripping chamber, before the water can be safely returned to the pool. Effective levels of ozone, if not stripped, can kill people, and have done so. To quote an article from the Journal of American Toxicology, abstracted by PubMed, "Ozone is one of the most toxic and ubiquitous air pollutants". Woe unto your pool's swimmers, if you allow ozone to remain in the water returning to the pool!.:eek:
Likewise, effective levels of ozone cannot be allowed to reach the point of chlorination, lest both the ozone and the chlorine be destroyed.
So, how have US ozone system manufacturers solved this problem? Easy! They just build systems that put ineffective levels of ozone in the pool water!:rolleyes:
The typical UV based systems used in the US are *safe* only because they are *ineffective*! They can "sell" only because Barnum's maxim about buyers is still true.
There are also some corona discharge systems sold hat are "intrinsically safe", a fact which is sometimes advertised as a 'feature'. But, again, an "intrinsically safe" ozone system is also "intrinsically ineffective" one!
To promote ozone as an "alternative sanitizer", as some manufacturers do, is simply dishonest!
Again, the reason is simple.
Pool sanitizers, in commercial pools, MUST be where the people are, in order to stop person-to-water-to-person transmission of disease pathogens. This is not a theoretical problem. The CDC has documented, summer after summer, public outbreaks following transmission via the "from their rear, to the pool water, and thence to your mouth" method . . . almost always courtesy of inadequate filtration and chlorination.
For ozone to be a pool sanitizer . . . it has to BE IN THE POOL! But, for safety reasons, ozone can NEVER be in the pool, only in the piping system. Therefore, something else must be. In the very effective German systems, the something else is always chlorine!
There's nothing new about any of this information. It was well understood in the potable water treatment industry, here in the US, and in both the pool and potable water industries, in Germany, LONG before I wrote my PoolSolutions' page on the topic. There have been incremental improvements in systems, but nothing that changes the basic facts of ozone chemistry.
Quote:
Originally Posted by grochmal
I'm surprised as well about the lack of info here about ozone.
. . .
The page that David refers to has some very old information on it (old in terms of ozone technology).
. . .
I am very excited about the prospects of using lower levels of chlorine and wished more people using ozone technology knew about this website and posted their experiences.
The reason for the lack of information about ozone systems is simple: the systems that work, are NOT appropriate for pools built for under $100,000, or pools which lack an onsite system engineer. If you are planning such a $100,000+ pool, and will have an intelligent on-site facility manager who can be trained to operate such a system safely and effectively, be my guest. You'll be able to get outstanding water quality that way.
But that's puts you outside the group I'm trying to serve here. My goal is to help people here, who are not in the $100,000+ pool market, achieve water quality that's nearly as good as what can be produced with such an ozone system.
In addition, on outdoor pools, exposed to the far more benign oxidizing effects of solar UV, the disproportion between the small benefits of effective ozone systems, and their large cost is huge.
Ozone does have benefits for indoor pool treatment, which is far more difficult than outdoor pool treatment. Successful indoor pool treatment, especially on heavily loaded commercial pools is difficult, and the difficulty is made worse by the burden of inaccurate or inapplicable information supplied by the pool industry. I have very deliberately kept indoor pool treatment issues segregated here. It's a small market, and a hard problem. There are solutions, but they are too site-specific, and too complex for a discussion directed at consumers, such as the one here at PoolForum.com .
I recognize the value of ozone for aquarists; in fact, I've several times finagled my way into see the systems used at the Tennessee Aquarium. (These systems do, by the way, generate high levels of ozone, which is stripped after passage through the detention chamber.) Ozone has value in aquatic treatment, precisely because its problems (insolubility) become a benefit: unlike chlorine, ozone is easy to get out of water!. Chlorine and its byproducts are simply intolerable in an aquatic environment . . . precisely because chlorine is so very effective at keeping water 'dead'. Ozone is less effective, but far easier to remove, and does not produce the byproduct stream that halogens do.
Live warm water is just 'naturally' pond like, but that's NOT what pool owners want. They want clear blue warm water which is, almost by definition, 'dead' water.
Aquarists, on the other hand, want water that is 'alive', but not 'too alive'. As you know, 'grochmal', maintaining a reef enviroment is labor and technology intensive. Multiple levels of filtration, protein stripping, ammonia control, oxidation by UV and ozonation, maintenance of saline balance, operation of biologically active filters, and more, are all part of the daily requirements for the serious aquarist. It is very fortunate, that virtually none of this is necessary for pool owners.
After all, for *most* pool owners, the pleasure does not come from the challenge of pool care; it comes from actually *using* the pool themselves. Chlorine makes this easy. Ozone just makes it more complicated and expensive.
So, the reason for the "lack of info here about ozone" is very simple. For owners of residential outdoor pools, ozone can only get in the way of achieving the goals I have for pool owners: that their pools become easier, cheaper, better and more fun!
I'm tired; it's late; and I've a chunk of my evening flogging a long dead horse! Hopefully, this will be the only time I have to do so this season!
Sincerely,
Ben Powell
"PoolDoc"
