Fresh Water Pool (cont.)
I haven't responded to the multitude of posts in this thread until now, so this is a long post. Some of the information that has been posted so far is from manufacturers who have a financial interest to not tell the whole truth or in some cases to lie or deceive in order to sell their systems. Some information in the posts is quoted or referenced from Wikipedia which is sometimes a good source and sometimes not -- anyone can edit Wikipedia. For the most part, I reference peer-reviewed scientific papers in respected journals whenever possible and use known science with detailed derivations so that anyone can verify them. There is a difference between these two types of sources and if you don't see or believe that, then don't bother reading the rest of this post.
merlock said:
Fresh water system!!!
Our pool builder installed a Barramundi Fresh water system, (In Australia, i'm not sure under what brands it's sold overseas), but basically it uses titanium electrolysis to oxidise everything to keep the water clean, and adds very small amounts of copper (through electrolysis automatically) as an added algae preventative measure.
It's great because the water isn't salty and doesn't smell of chlorine, save on maintenance costs...it's just like swimming in bottled water lol so when u inevitably swallow a mouthfull of water, it's just like tap water. Of course you still need to add calcium if its a concrete pool, buffer and pH adjusters but u don't notice these at all. Having previously maintained a salt-water pool in another house, which was previously chlorine this is by far the best to swim in and maintain.
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Finally if you're installing solar, go for a modular panel system over the horrible black rubber draping your entire roof, its much more space efficient and works better on windy/cooler days than the rubber, however it is substantially more expensive.
The system is described in more detail at
Barramundi Freshwater Pools, but note that it is also under
Ecosmart AustralAsia (this may be related to ECOsmarte in the U.S. that recently came out of bankruptcy -- note the URL of "ecosmarte" for
EcoSmart AustralAsia). Notice that in the first link detailing the system there is also a "Chlorine Dosing Pump" and the final statement on the page is "
* Subject to local regulatory conditions, in some areas the use of a small additional sanitiser is recommended according to government regulations." The owner's manual for the system is
here. There are specific operating parameters described in this manual, but I'll cover that later in this post.
The pool water is not just like tap water. There is no fast-acting sanitizer in the bulk pool water (I'll write about the copper ions later in this post) so you will be swallowing some of your own and others fecal material including their bacteria which will still be very much alive. Same is true with viruses and other pathogens. This is why this system is not allowed in any commercial/public pool, even in Australia, without chlorine. You can read
this page from the Australian Pesticides and Veterinary Medicines Authority (APVMA) on why copper and silver ion products are NOT allowed by themselves in commercial/public pools and why copper is only registered as an algicide and not a disinfectant/sanitizer. Adding an oxidation system does not provide a sanitizer in the bulk pool water so is not sufficient to pass the Australian standards let alone the
EPA DIS/TSS-12 standard in the U.S.
For the solar system, when you say "modular panel system" are you referring to glazed (glass-enclosed) panels? It is true that they are better in conditions where the air temperature is cooler, especially when there is wind and that such systems are around 3 times more expensive. They are not, however, as efficient when the air is warm and calm. A comparison of solar panel systems is in
this thread.
merlock said:
No actuallly, the system uses an electronic oxidiser to introduce oxygen into the system, and uses an ioniser to introduce Cu2+ ions at 0.3-.07 ppm conc, (see barramundipools.com.au). The cu2+ ions acts as an algaecide, the system is run for 8hours a day in summer, 4 hours in winter.
The only chemicals added to the pool are a sodium bi-carbonate buffer (40-80ppm), and CaCl, to prevent leaching of calcium from the concrete. At the moment we are also adding HCl acid to counteract the effects of fresh concrete, however this is only temporary and the Cl quickly evaporates leaving the pool Chlorine free, far from a septic tank.
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Btw i have a Bsc. Bio-tech, which basically means i'm a chemical engineer with a degree in molecular biology, so i know a thing or two about sanitation lol, seeing as a uni project was to design a sewerage treatment plant.
That's great that you are a chemical engineer with a degree in molecular biology. Read later on when I link to how copper ions work at pool concentrations and what they can and cannot kill or control for sanitation. However, what do you mean when you write that the "Cl" from HCl "quickly evaporates"? What are you talking about? The Cl in HCl is chloride ion as in salt and remains in the water. It does not evaporate and it never was the same as chlorine which is in a completely different oxidation state (+1) than chloride (-1). Adding hydrochloric acid (HCl) is not adding chlorine to the water. It lowers pH and results in more salt.
I'll write later in this post about the recommended concentrations for water chemistry with this system and why it is corrosive to plaster (i.e. tends to dissolve plaster, concrete, etc.).
merlock said:
Oxygen not a sanitiser? You do realise that i'm not talking di-atomic oxygen? I agree di-atomic isn't generally (excluding anaerobic organisms). However in the electrolysis of water O- is present, as O- cannot exist on its own for more than a pico second or two, it reacts with water to form H2O2, a much much more potent disinfectant than Cl, which reacts to form HOCl in water when added. H2O2 is used by every cell in our body to destroy pathogens during phagocytosis, used in most hospital-grade bleaches instead of Cl based bleaches.
The great thing about H2O2 is that it quickly decays back to water and O2. While yes this site advocates against the use of H2O2, i believe they are referring to the addition of aqueous hydrogen peroxide and not specifically to its generation within the sanitation system by electrolysis. Within the chamber the H2O2 levels are high enough to quickly kill any pathogens, outside of the chamber they are not very high as obviously that would be irritating. However they are at high enough levels to offer some residual protection. Again i must stress my original point that the system is run every day to maintain the residual levels and to kill any new pathogens. Yes you cannot turn this system off without adding a sanitiser, that is a weakness however while it is operational it is better at sanitation than chlorine as the entire volume of the pool goes through that pump every 3 hours of operation.
Don't believe me?
http://en.wikipedia.org/wiki/Hydrogen_peroxide
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As for copper staining...the copper is maintained at a level of 0.3-0.7 ppm, the safe drinking standard is 3.3 ppm, so the stuff you get out of your tap can have a higher concentration than my pool. I quite agree that in higher concentrations it can stain, but not at such low concentrations. If you go and buy a bottle of algaecide, look in the ingredients...there are two main types and one is just aqueous copper.
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As noted in the link to the product I gave earlier, this appears to be either an ozonator system or, more likely from their description of inline titanium plates in the water, basic oxidation providing a small amount of hydroxyl radicals, hydrogen peroxide, perhaps a tiny amount of ozone, and some chlorine depending on chloride level. However, it mostly produces oxygen gas. I write more about this later in this post.
The safe drinking water standard in the U.S. has a Maximum Contaminant Level Goal (MCLG) for copper of 1.3 mg/L (ppm) as shown
here. The
National Water Management Strategy (NWMS) Drinking Water Guidelines in Australia set a health guideline limit of 2 mg/L (it's 1 mg/L for asthetics) so I don't know where you are getting a safe drinking water standard of 3.3 -- what is your source for this?
David121 said:
You're both wrong.
Bama Rambler: Cu in its ionic form can be used as a residual sanitiser, the Cu2+ ions are attracted to the cell walls of bacteria and algae during the growth stage resulting in their death. It is however only effective on actively growing organisms. Viruses are also inactivated but i won't go into detail here.
Merlok: The electrolysis of water with titanium electrodes (as used by the barramundi system) generates ozone directly, not H2O2. The ozone is highly corrosive and much more potent than chlorine, however it decomposes to O2 very quickly leaving no residual ozone in the system.
The system uses both processes to sanitise water, the copper prevents any growth, as cell division is inhibited and non-dividing cells/copper resistant are destroyed by the ozone when it passes through the chamber.
I've been using this system for almost 4 years now with no problems, however as Merlok said it does have to be run every day and i don't know how it goes with the shutting down for winter, as i've never bothered because it requires no additional chemicals anyway and just turns on with the skimmer.
Source:
http://www.wwdmag.com/Bacterial-Control ... rticle4227 ,
http://nochemicalpool.com/oxidization.php
As noted in
this Barramundi Freshwater Pools link, the oxidation unit is a corona discharge (CD) ozonator. However, their description is inconsistent with a real CD ozonator where the discharge (electrical spark) is done in air where some of the oxygen is converted to ozone and then injected into a water stream. The Barramundi description says that water flows through the chamber with the titanium plates in which case this isn't really a CD system but more like an "active oxygen" system that generates mostly oxygen (which doesn't do very much), a very small amount of ozone and hydrogen peroxide and hydroxyl radicals and, depending on chloride level, some chlorine as well. The
ionization system sounds more traditional with electrolysis of a copper plate producing copper ions. Based on
this diagram, it certainly looks like this is an inline system where water flows through both the ionization and oxidation chamber so this would certainly not be a CD ozonator system (note that the two "injectors" are for CO2 or acid for pH control and chlorine for sanitation with the latter required by law in commercial/public pools). So are they lying on the website about this being a CD ozonator? Why don't those of you with such a system call the manufacturer and have a detailed technical discussion about this, but don't let them B.S. you -- question them in detail about how they create a corona discharge with water flowing between the titanium plates.
As for copper ions in water, please read
this post. There are numerous scientific peer-reviewed papers in respected journals detailing how copper ions at pool concentrations would be completely ineffective against bacteria that normally reside in the human body such as in the G.I. tract or blood-borne pathogens. The reason is that blood serum has from 0.7 to 1.5 mg/L (ppm) copper ions so bacteria in the body have mechanisms for completely tolerating this level of copper which is around the level or somewhat higher than found in pools using copper ions to prevent algae growth. This basically means that copper ions in pool water are ineffective not only at killing fecal bacteria quickly, but even in preventing their uncontrolled growth. Copper ions are reasonable against Legionella, but not much else that is of concern. Note that many alternative sanitation websites refer to EPA approval of copper in hospitals, but neglect to mention that this is solid copper surfaces which is not at all the same thing as bulk pool water disinfection at rather low copper ion concentrations. Copper ions are also generally not very fast at inactivating viruses or protozoan oocysts and I list specific references for this in my post. Can you please provide specific references to where copper kills viruses reasonably quickly?
merlock said:
Sorry, i made a mistake...but H2O2 can be produced as a bi-product even if its not the primary product, still ozone is a more potent oxidiser again. Point being on its own neither copper ions (NOT THE chelated stuff) or ozone can sanitise a pool but together they overcome each other's short comings making a far superios system.
The EPA might not approve it (in your country) however i've toured a bio-tech company which produces FDA approved drugs using an ozone system to purify their water source for the manufacture process, FDA>EPA. Before you say its different because its not an open system like a pool, it is in this situation as the water is reclaimed from a fermentation tank and FDA regulations are much more stringent than any one elses, so if its good enough for them its good enough for anyone.
Where are you getting that copper and ozone on their own aren't sufficient but together they are? As noted above, copper ions are completely ineffective against a wide range of fecal bacteria and blood-borne bacterial pathogens while any ozone or other oxidizers produced in the chamber will only affect pathogens floating into that chamber. They will not do anything for pathogens in the bulk pool water including those that may attach to pool surfaces and that could form biofilms in some cases. Basically, copper ions are a good algicide (notwithstanding staining and blond hair turning greenish issues), but are not a fast-acting disinfectant at pool concentrations.
merlock said:
Did i not make it clear that the plant reclaims its water? Tap water is purified, passed into a fermentation tank containing mammalian cells which have been genetically engineered to produce a specific product. The water is reclaimed from the tank, purified and put back in...so like a pool...only if a single bacterial cell is found in the the fermentation tank the entire batch (worth hundreds of thousands of dollars in media alone) is dumped because it won't pass FDA regs.
You clearly have no idea just how easily bacteria can contaminate something, this system is designed so that you could take a dump in the water before its purified and there still not be a problem.
The ozone levels purifying water are far more powerful than the one used in your pool (I also doubt that the fermentation tank holds 10,000 gallons or more) and as noted in posts in this thread, there isn't any reintroduction of pathogens in a closed system. In a pool, you are shedding bacteria from your skin, mucous and fecal matter (as well as viruses and protozoan oocysts if you are infected) and can transmit these to other people since there is no bulk fast-acting sanitizer in the pool water. There is very little residual ozone or other oxidizer making it to the bulk pool water and in fact real ozone systems are designed to prevent too much ozone from reaching the bulk pool water in order to prevent ozone outgassing since that is a regulated and hazardous gas.
Also note that one turnover of water only has around 63% of the pool water make it through the chamber; two turnovers has 86% of the water pass through at least once; three turnovers 95%; four turnovers 98%. Of course, this assumes ideal mixing, but any pathogens stuck to pool surfaces would not make it to the chamber at all.
David121 said:
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You do not have to run it 24/7, in our pool the water is turned over by the pump every 2.5 hours (25 000L/Hr, 65 000 litre pool). In summer it is run for 8 hours per day, it needs to be split roughly equally throughout the day. So in summer effectively the entire volume of the pool passes through the chamber 3 times a day. Inside the chamber the titanium plates have a low current passed across them causing a corona discharge and hence the production of Ozone. As Merlok points out the O- ion can react with water but in preference reacts with O2 to form O3, i.e ozone.
I'm sure the efficacy of Ozone as a sanitiser is not in-dispute here, i'm sure we can all agree that any virion particle, or living organism when exposed to high ozone levels is destroyed. However this is only in the chamber, this is the more active side of the system and i recognise that Ozone plays no part in the residual sanitation of the pool.
Copper in its ionic form is however a residual sanitiser.
The copper is added electronically by a second electrolytic cell as Cu2+ ions. It is not added as a chelated compound. In its ionic form Cu prevents the ACTIVE growth of organisms. Similar to penicillin it prevents the synthesis of cell walls when an organism tries to actively grow. However like penicillin it is not effective against organisms that are not undergoing growth or division. So yes it is completely useless on cells which are not making any changes to the cell wall. If a cell however is not making changes to its cell wall then it can't really be doing much can it? Certainly not dividing.
Cu2+ can bind to some virion particles rendering them inactivated, however this is ultimately determined by the virus type, the presence of a nucleocapsid, or matrix will change the effectiveness.
The page warning against alternative systems mentions coppers use as an effective drinking water sanitiser, it may have a slow total kill time, i.e killing all cells but it does prevent any active growth of cells. But with the pool water being turned over at least three times a day through the ozone chamber everything is removed from the system with in 8 hours (obviously depending on how you have it set up.)
As for the staining, yes copper can stain, however not in its ionic form. In its ionic form it cannot form a solid and remains in solution, if you however add some carbonate or sulphate ions you will chelate the copper and it will stain. In this system as the only other chemicals added are a buffer (sodium bicarbonate) and CaCl (to protect form leaching Calcium from the concrete) it is not a problem assuming the correct pH and TA parameters are kept.
Sodium bicarbonate has a pKa value of 7.2, i.e at pH=7.2 according to the henderson-hasselbach equation, pH=pKa + log (salt/acid) the concentration of carbonate ions is 50% as compared to the acidic form (CO3 2- vs. HCO3-). So to prevent the carbonate in the buffer reacting with the Cu ions, forming copper carbonate and staining the pool the pH has to be maintained below 7.2 (preferably 7.0).
Assuming those parameters are maintained there is no issue what soever with staining.
When the pool was first built due to the concrete rapidly raising the alkalinity as it cured, we did have a problem with the copper reacting and then staining, however that was due to my laziness in adding acid and the stains disappeared after a few weeks.
This system has been approved for domestic use in Australia, and is now used by most of the premier pool builders.
In order of sanitation systems i prefer this the most, however if you don't trust it chlorine in my opinion is nicer to swim in than salt because salt always leaves u feeling crispy afterward.
Read my earlier info and post link on copper ions since much of what you write is incorrect about copper ions at pool concentrations. In particular, read the scientific papers and ask your biology professors about the bacterial mechanisms for handling copper ion concentrations found in blood serum.
I already linked to the APVMA page about copper and the system is not "approved" as a disinfectant or sanitizer even for domestic use. Note that APVMA on
this page explicitly states "
The APVMA has previously warned owners of pools and spas to make sure, for health reasons, that when using water sanitising devices based on silver or silver and copper, they should also use registered pool chemicals containing chlorine or bromine." Also, look at the
PUBCRIS database where you will not find any registration under "Barramundi" though you will find copper rods registered by Ecosmarte
here as an algicide (not a disinfectant/sanitizer). Very often, alternative sanitizer websites will tout their EPA or APVMA registration number, but neglect to point out that it is only as an algicide. They can make no claims on websites, product labels, brochures, etc. about being a sanitizer or disinfectant (though sometimes this slips through on occasion -- the EPA is currently re-evaluating PristineBlue, for example).
merlock said:
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Our pool is 12.5m long, consisting of a swim lane and widening out at the ends, deep end 5.0m wide, shallow 3.5, middle of pool is 2.5m wide. Average depth is 1.2m, freeform shape...Concrete, fully tiled.
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pH is maintained between 6.8-7.2 (current reading 7.0)
TA is maintained at 40-100, currently 49ppm (using ColorQ testing system)
Copper maintained at 0.4-0.7ppm, currently 0.65ppm ideally meant to be 0.7ppm.
Calcium maintained at 400ppm, currently 350.
Phosphate: 0
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Again, this system is NOT an approved disinfectant or sanitizer system, even in Australia. Copper ions at swimming pool concentrations are approved only as an algicide, period. The oxidation system is not approved as a swimming pool disinfectant or sanitizer since it does not leave a residual in the bulk pool water.
Let's look at the recommended water chemistry levels as described in their product manual:
pH: 6.8 - 7.2
Copper: 0.4 - 0.7 ppm
Calcium: 400 ppm (if it falls below 250 ppm, raise to 400 ppm)
Phosphate: 0 (they don't say how you get that low -- phosphate removes only get down to around 75-100 ppb)
Total Alkalinity: above 40 (40 - 100)
The reason for the low pH recommendation is to prevent copper staining. However, this makes the saturation index very low. Only the most generous of the above readings using a pH of 7.2, Calcium Hardness (CH) of 400 ppm, Total Alaklinity (TA) of 100 ppm, assumed Cyanuric Acid (CYA) of 0 ppm, and temperature of 85ºF, result in a saturation index of around -0.1. If I use the low-end numbers of pH 6.8, CH 250, TA 40, I get a saturation index of -1.0 which would likely be corrosive to plaster, concrete and grout surfaces. The tendency to dissolve calcium carbonate would be very strong.
Also, if you were to keep the TA much higher than 40, you would find the pH would tend to rise over time due to carbon dioxide outgassing since pools are intentionally over-carbonated and a low pH with higher TA results in faster carbon dioxide outgassing which makes the pH rise. So you have a real catch-22 here. You could have the CH be much higher where a CH of 2000 ppm would let you have a pH of 7.0 and TA of 40 ppm with a saturation index of -0.2 which is more reasonable and the pH would probably not rise too quickly.
David121 said:
Sorry but what did you mean by corrosive at 7.0? In biology pracs we use sodium bicarbonate in a certain ratio to keep the pH at around 7.1 as a biological buffer, our blood uses the same system to maintain pH. Rainwater has a pH of 5.6 to 6.3...
Also our skin is naturally acidic so the lower pH doesn't have adverse effects...i have contact dermatitis which gets inflamed whenever i swim in chlorine or salt water pools but is fine in the "fresh" water pool.
I can't offer any more science to back up my claims, i haven't done a detailed study and i'm not aware of any independent testing...so i'm just trying to apply my own knowledge to explain it.
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See my info above where "corrosive" is referring to dissolving the calcium carbonate in plaster, concrete and grout surfaces. Pool water exposed to such surfaces is supposed to be saturated with calcium carbonate, but the very low pH level you need to prevent copper staining and the low TA needed to prevent rapid pH rise causes the saturation index to be very negative unless the calcium hardness is very high.
David121 said:
After reviewing ozone only systems, they claim to leave a residual level of ozone in the pool. I can't verify whether the concentration is high enough however to instantly kill things...
Ozone systems only claim to have very low levels of ozone as a residual and in practice it can't be very far into typical sized pools since too much ozone in the water would lead to too much outgassing and it's a regulated gas being a health hazard (the ozone limit set by the FDA for devices is 0.05 ppm in air as described in
this link).
Richard
I'm not qualified enough to comment to the likes of Chemgeek and other on this board, but will await their thoughts.
