Just to be more complete in the discussion with Wendy about EcoSmarte, she did not fully represent what was being done for oxidation when she described the titanium coated with noble metals. If you look at the EcoSmarte website and click on the Science Summary link, they describe what is being done (sort of). It's essentially electrolysis of the water which produces mostly hydrogen and oxygen gases, but probably due to their proprietary coatings of noble metals and use of sufficient voltage, they also say they produce some amounts of hydroxyl radical, atomic oxygen and hydrogen peroxide.
Their table of Oxidation Reduction Potentials is incorrect in that they list "Sodium Hypochlorite" with a symbol of salt (NaCl) and give it an ORP which it does not have. I think they meant hypochlorite or OCl- since the ORP is roughly close to that. But then they say that each EcoSmarte oxidizer (in bold) has a higher ORP than sodium hypochlorite and that is very misleading because some of the ORPs listed are for standard conditions (1 Molar concentrations) and not for the conditions (including pH) of the pool. There really isn't a separate hypochlorite and hypochlorous acid ORP -- they have a single ORP since they are in equilibrium and the ORP is higher than that of oxygen. Interestingly, the oxygen ORP they list is closer to the theoretical number in pool conditions, but this is still a theoretical number. Actual ORP sensors tend to measure dissolved oxygen ORP at around 300-400 mV while chlorine, even with CYA, is around 650 mV.
Anyway, the main problem is that there is no indication that the much more powerful oxidizers are produced in any significant quantities except for their claim that "20-80 grams per minute of oxygen radicals are created from the water". All they claim they have demonstrated is that dissolved oxygen measures an increase to which I say DUH! Oxygen is clearly produced through electrolysis, but water is already saturated with oxygen due to its equilibrium with the air so adding more isn't going to do any good except to cause oxygen bubbles to percolate through the water (as well as hydrogen gas bubbles at the other electrode) and may lead to a SMALL amount of super-saturation as dissolved oxygen (DO). Anyway, back to the 20-80 grams per minute claim for oxygen radicals. Let's assume that they are talking about atomic oxygen with roughly 16 g/mole molecular weight. That's 1.25 - 5 moles of atomic oxygen per minute. That's 96485 Amp-sec/mole * 1.25 moles = 120,606 Amp-seconds minimum or over one minute (remember they said "grams per minute") that's 2010 Amps. That's not very low current, now is it! The electrolysis at around 2 amps would produce milligrams per minute, but most of that would be oxygen gas. So who knows what the REAL number is for the amount of oxygen radicals being produced.
waterbear (Evan) talked about this earlier, but their claim about EcoSmarte electronic oxidation keeping calcium carbonate from precipitating by keeping it in the soft bicarbonate form is ridiculous. It's completely dependent on pH, TA, CH and temperature. They say they have a successful history up to a pH of 8.3 and CH of 442 ppm -- well, sure, if you have the TA be low enough then you can ensure no scaling will occur. At a TA of 50 ppm, the saturation index with their pH of 8.3 and CH of 442 is +0.6 which is high, but probably not quite high enough to show scaling. At a TA of 100 ppm (CYA of 30 ppm), it would be +0.95 so would likely start to show scaling. There's nothing about the EcoSmarte system that changes that. At a pH of 7.5 they should be able to handle a CH of 2000 ppm or more before scaling becomes a serious problem (saturation index of +0.6 with TA of 100). And maybe when they talk about their successful history up to a pH of 8.3, they are referring to initial water, not the pH they normally target which is close to 7.0 and of course would not show scaling even with rather extreme TA and CH.
They say "Calcium is managed in bicarbonate form CA(H(CO³)² to 155Â°F under methods testing approved by ETL/EPA Labs and developed by Ecosmarte® in 1995. Alkalinity of the water is also primarily bicarbonate, reducing corrosion tendencies. These principles are consistent with Langlier theory, though not widely known in the water industry. Most Canadian and European water analysis are now measuring bicarbonates." Well, we already talked about the saturation index so principles consistent with that index would be, perhaps, controlling pH, TA, CH and temperature?
They use copper ionization most likely for algae control. They say "No constant introduction of copper occurs and the residual sanitizer in the pool is recognized by the National Sanitation Foundation (NSF) and the U.S. Environmental Protection Agency." Well that's interesting isn't it. Where does the "residual sanitizer" come from. They can't claim that copper is that sanitizer -- a pesticide, yes, a sanitizer suitable for killing bacteria quickly, no. But I found on other sites of theirs that in fact they do claim that the residual copper is the sanitizer.
They then go on to list a series of chemical definitions. The copper kill rates table is interesting, but doesn't mention the fact that the kill rate is very slow compared to chlorine. In fact, it isn't much different then using PolyQuat 60 which isn't just an algaecide and a clarifier, but also disinfects, but is slow-acting and works by the same mechanism of blocking ion channels. So using copper to stop bacterial growth and then a strong oxidizer to destroy that bacteria is reasonable in a water system exposed to the copper for a long enough time and for it to get circulated to the oxidizing system, so for preparing drinking water this may be reasonable. But when bathers are constantly introducing bacteria into the water, you want that bacteria killed in the time it leaves as fecal matter until it gets splashed into your mouth (sorry for the graphic description -- I couldn't figure out another way to say it). You can't wait an hour or more. Disinfection with copper alone takes at least 100 times longer than for chlorine alone (and that's with CYA in the water). Most "easy-to-kill" bacteria have 2-log (99% kill) CT values of 0.04 to 0.08 and the disinfecting chlorine amount in pools is around 0.05 ppm so that means a 99% kill in about a minute or so. The 50% kill time for chlorine in pools is around 7 seconds which is far faster than the bacterial reproduction rate of 15-60 minutes. The copper kill rate table shown on the EcoSmarte webpage just indicates that you need that much copper to kill bacteria faster than it can reproduce since most bacteria double in population in 15-60 minutes. So you need enough copper in the water to kill faster than that window of time and that concentration (with some safety factor) is what is listed in the table. Their system keeps from 0.4 to 0.7 ppm of copper ions in the water. So the copper takes around 10 minutes or so to kill half the bacteria before it doubles in population while the chlorine takes around 7 seconds to do the same thing.
On their "Pool and Spa Systems" web page they say, "The system uses copper ionization, which has a faster and longer kill rate than chlorine or bromine." which is simply not true since copper is NOT a faster kill rate than chlorine or bromine.
They talk of using CO2 for lowering pH, but they don't mention that this will increase TA merely exacerbating the problem of having the pH rise in the first place! [EDIT] I must correct myself here. Injecting CO2 lowers pH with no change in TA, as it's the exact opposite of outgassing. However, it does add to carbonates so with the lower pH at the same TA it DOES increase the tendency of the pH to rise compared to using acid which would lower both pH AND TA with less resulting tendency for the pH to rise. [END-EDIT]
It's not that copper doesn't have value, but saying that it can be used without any sort of fast-acting disinfectant is irresponsible, and probably illegal in some jurisdictions (anyone have any info on the requirement of using chlorine with copper ionization systems?). If their system really does oxidize at a fast rate (and clearly their reported numbers are wrong), then you could probably use a lower level of chlorine in the water as a fast-acting sanitizer, but I wouldn't eliminate it completely. Realistically, the risk in a residential pool is low unless you treat it more like a commercial pool by having a large swim party and somebody goes in the water with some fecal-to-oral disease.