Pristine Blue

[pooldude]

Anyone use Pristine Blue? They say it's 100% chlorine free and has all the necessary certifications.

I'm thinking of getting away from chlorine but am a little hesitant due to my ignorance and lack of experience.

[chem geek]

The sanitation and algae prevention in Pristine Blue comes from copper sulfate, so copper ions. Copper is not a fast-acting sanitizer. It kills bacteria even more slowly than silver ions and that's far slower than chlorine. It is very ineffective against viruses though it is good at preventing algae growth. It is therefore unsuitable by itself for preventing transmission of disease from person-to-person which is why such systems are not used in commercial/public pool environments.

As for the certification, the product contains copper sulfate that is an EPA approved pesticide since it does kill algae, but it is NOT certified as a Swimming Pool Water Disinfectant since it would not pass the stringent tests, especially the laboratory test. The NSF/ANSI Standard 60 is just a drinking water standard for safety and says nothing about disinfection rates. It is deceitful for Pristine Blue to use the EPA registration and NSF/ANSI Standard 60 to imply anything about disinfection.

There are only 3 EPA DIS/TSS-12 approved disinfectants: chlorine, bromine and biguanide/PHMB/Baqua. In addition, it appears that silver ion used in conjunction with higher levels of non-chlorine shock (monopersulfate, MPS) are approved, but only at high spa temperatures (i.e. not for pools). That's it. Metal ion systems, ozone, UV, etc. are NOT approved as standalone disinfectants and they cannot use such wording (i.e. disinfectant) on their labeling. All such systems must use a supplemental EPA-approved disinfectant to pass DIS/TSS-12.

Now, that said, it's all a spectrum of risk and the risk is far lower in water containing metal ions than water having none. The main concern that DIS/TSS-12 addresses is preventing disease transmission from person-to-person in commercial/public pool situations since one sick individual can spread disease to many if the water is not disinfected appropriately. In a residential situation, simply controlling bacteria growth helps a lot. But as I say, it's a spectrum of risk and only the pool/spa owner can decide the appropriate level of risk they are willing to take.

Also, see my post here for more information on the publicized issues with chlorine pools.

Richard

[Larry]

Thanks for this great post Richard

I have been aware of Pristine Blue for several years, though my dealings with chlorine-free pools has been very limited. Our regional distributor has always tried to sell me on the "only halogen-free EPA approved disinfectant" line. I have even been presented with copies of EPA and NSF certification documents that purportedly back up the distributors sales pitch.

I only have one pool using Pristine Blue, an indoor heated pool. The pool is intermittently opened to groups of children for recreation and is only used by 2-3 swimmers per day most of the time. I have found that the pool responds well to a chlorine shock treatment every 2 weeks, and weekly when the kids come to swim. The best part of the pool is that since converting from chlorine, the absence of chloramines (and the chlorine smell) has made the pool better for the swimmers. I think I need to reevaluate the pool and consider a more regular chlorination program based on the information you have given.

Your post has opened my eyes.

[Me...]

An interesting read here too.

http://findarticles.com/p/articles/mi_m ... i_15602969

[noob]

Great find Me... I never thought ozone could be so effective.

This thread has really opened my eyes

[Me...]

Ozone is the one of the best things you can do for a pool or spa. Unfortunately some of the fantastic things you read about the benefits can not be done for $100. Or even $200. A small UV Ozone generator tucked under the skirt on your Hot Tub can be quite beneficial but all too often people are expecting or led to expect the benefits it would take a multi thousand dollar system to achieve.

UV systems are another good thing but you should have 100% flow through them and the flows through the units are often 2-3 times what they should be and so it too can get some bad knocks. I remember electric heaters that were rated for 5-10 gpm and had 30 gpm or more going through them. Small wonder the elements or probe wells were quite often shot in short order or the heater didn't seem to be very efficient. Copper/Silver Ion systems are also slipstream systems and they get plumbed into the main lines and are exposed to extreme flowrates which erode the electrodes swiftly instead of allowing a small current to blow off electrons slowly.

[chem geek]

Note that chlorine is still used in the systems that use ozone (or UV, for that matter). The Free Chlorine (FC) level is lower at 0.2 to 0.4 ppm or so, but remember that's with no CYA in the water. Technically speaking, this is identical in active chlorine (hypochlorous acid) concentration to around 4 to 6.5 ppm FC with 20 ppm CYA. This only validates the point I was making of the foolishness of using no CYA in indoor pools (using too much CYA is also a problem).

The problem with using the low chlorine level with no CYA is that it does not provide a buffer of chlorine in case there is a strong chlorine demand locally in the water, such as that from a urinary discharge that can often happen with children in the water. If the chlorine gets used up, then there is no disinfection to prevent person-to-person transmission.

The main purpose of the ozone is to provide further oxidation. It does not prevent chloramine formation, per se, but the lower active chlorine concentration helps there. I'm just saying that one can have the lower active chlorine concentration by using some CYA, independent of whether you supplement with ozone or not. More technical detail about this, at least with regard to nitrogen trichloride which is an irritating disinfection by-product potentially indicated in the respiratory and ocular problems is here.

I'm not saying that ozone or UV aren't helpful -- they are -- but rather that what is obscured is that it is the high active chlorine concentration that may have been a primary source of the problem.



Richard

[chem geek]

Our regional distributor has always tried to sell me on the "only halogen-free EPA approved disinfectant" line. I have even been presented with copies of EPA and NSF certification documents that purportedly back up the distributors sales pitch.

Can you take a look at the EPA documents to see if it's simply registered as a pesticide or it is really registered a swimming pool disinfectant (under DIS/TSS-12)? This link is the EPA page on data submitters for pesticides and this link is to the data submitters list. Earth Science Laboratories that sells PristineBlue isn't listed, but they probably piggy-back their registration with the "copper sulfate task force" that is listed and you should be able to search for the registration number in any event. Companies often pool together to get EPA registration since it is an expensive process -- they then only need to demonstrate that they are using the same chemical and instructions for use as one already registered and to show that they meet labeling requirements. Again, this is not for registration as a swimming pool disinfectant, but rather as a pesticide which is a far easier certification -- there is no specific efficacy requirement -- pesticide registration is mostly to prevent misuse and that they do not pose undue risk to people and the environment.

Richard

[chem geek]

Sorry for the multiple replies, but I got a message that there is a maximum of 3 URLs allowed in a post.

One MSDS for Pristine Blue is here ([EDIT] that link is dead, but this one seems to work [END-EDIT]). This article is pretty good at explaining alternatives to chlorine and how ones like metal ions don't kill pathogens quickly in the bulk pool water while others such as UV and ozone don't leave a residual for killing pathogens at all. The most notable point is that the manufacturers/distributors of these products aren't always up-front about how they cannot be used without chlorine (at least they cannot legally claim to be a disinfectant).

Richard

[Me...]

I don't really think lowering the FC to .2 is feasible exactly for the bathload reasoning. In fact the Health Board here will only allow .5 if it is a proper CD Ozone system. The amount of chlorine at 1.5ppm consumed with good Ozonation will be substantially less anyways. Which means less acid and therefore less Bicarb etc.

Ozone is devastating to chloramines but of course only in the contact chamber because with slipstream systems we don't really aim to have Ozone out in the Pool. Chem Geek will have the lingo for chlorine in various forms as the water goes through the various pH changes, but Ozone will more readily attack the chlorine in the forms it takes at higher pH levels. Hence the need to keep pH under control, which is easier if the system works well and keeps chlorine use to a minimum. So if you have a too powerful Ozone system combined with too small a contact chamber and a high pH pool, you stand a good chance of actually raising chorine consumption.

And, if you follow with the guideline that .2ppm combined is the upper limit, and that it takes 10 times the FC to destroy the combined chlorine, then it follows that a 2 ppm FC reading will theoretically be getting rid of the combined chlorine 24/7. Therefore whatever the system, if the combined are always a problem, keep raising the FC until they stop. Once you find your pools threshold you should be able to start lowering the FC until the combined become an issue again.

[chem geek]

My reference to the 0.2 to 0.4 ppm FC was from the article you linked to. So I'm glad you agree that it isn't particularly feasible for higher bather loads. That's where CYA becomes very useful as it holds chlorine in reserve releasing it as needed while keeping the active concentration at a lower level that slows down disinfection by-product formation. The reason no one seems to think of it this way in spite of the clear science known since at least 1974 is that the chlorinated cyanurate industry only talks about CYA protecting chlorine from sunlight. You really should read the introductory sections in the paper in this link. You see, if the industry started to talk about how low it makes the active chlorine concentration, then someone might ask if this affects algae growth and then someone would realize that continued use of stabilized chlorine products raises the CYA letting algae grow if you don't proportionately raise the FC. That is, the product (e.g. Trichlor and Dichlor) has a built-in obsolescence requiring use of algaecides or phosphate removers in many cases.

As you point out, ozone is a strong oxidizer and will oxidize chemicals that chlorine won't or that chlorine simply combines with (i.e. combined chlorines). This isn't helpful in the bulk pool water where monochloramine will still form quickly and it isn't particularly necessary with the normal oxidation of ammonia since that is still mostly complete before even one turnover, but it is very useful for persistent combined chlorines or for organic substances that more slowly combine with chlorine. Also as you point out, you have to have a powerful enough ozonator for a pool -- most residential units aren't strong enough. Ozone can oxidize chlorine to chlorate so you are right that the conditions should be such to minimize that -- I'm not familiar with which conditions are best for that. I suspect that using ozone in a light bather load pool may end up using more chlorine while in a heavier bather load pool it may lower chlorine use -- the difference being whether the ozone can eliminate bather waste quickly enough so with higher concentrations of bather waste from higher bather load that's more likely.

As for combined chlorine and the 10x rule, it's wrong. The 10x rule came from the stoichiometry of chlorine oxidizing ammonia, not chlorine oxidizing combined chlorine (such as monochloramine). It takes 3 chlorine molecules to combine with 2 ammonia molecules to fully oxidize them to nitrogen gas (and hydrochloric acid). That's a ratio of 1.5. When you convert the units to ppm for each compound, where by convention chlorine is measured as ppm Cl2 (chlorine gas) equivalent while ammonia is measured as ppm N (atomic nitrogen) equivalent, then you get a ratio of 7.5. Due to some side reactions, the reaction gets to completion with a ratio of 8 to 10 chlorine to 1 ammonia. This is where the 10x came from. However, Combined Chlorine (CC), such as monochloramine, is not measured in ammonia units, but in chlorine units as the test is essentially a chlorine test. Also, of the 3 chlorine to 2 ammonia, two of the chlorine are already combined with two ammonia to form two monochloramine. It technically takes only 0.5 times the amount of measured CC to oxidize it, though taking into account side reactions it's slightly higher, but using a rule of at least having an FC that is equal to the CC is sufficient.

The above discussion regarding the 10x rule is with regards to stoichiometry, so having enough chlorine to not run out. It is not about reaction rates so having a higher FC will make any chlorine reactions go faster. So your rule of raising the FC until your CC level is lower relates to this reaction effect, but technically it's not the FC alone that matters but the FC/CYA ratio if CYA is present because reaction rates are based on the active chlorine (hypochlorous acid) concentration and not on FC which mostly measures the chlorine reserve (chlorine attached to CYA as chlorinated cyanurates).

If one has an FC/CYA ratio of 10% or more, then one has oxidation of ammonia in a matter of hours in pools. If the bather load is higher, then a higher FC/CYA ratio of 20% would speed up the oxidation to hopefully keep up with the bather waste introduction rate. Unfortunately, though ammonia oxidation is well understood, the oxidation of urea is not and urea is by far the largest component of sweat and urine. Since urea oxidation is slower, it will build up until you get to a steady state of bather waste introduction vs. oxidation by chlorine. Again, this is where the ozone can be very helpful as a supplemental oxidizer.

Richard

[Larry]

Richard, this article you pointed out is extremely telling. Below are some quotes which I tried to verify on the official Pristine Blue website. It seems their forum has been inactive for months and is now home to spammers. There is no claim that PB is a chlorine alternative and they prefer to call it a "non-chlorine" product.

... But what is not clear is whether PB can be relied upon as a stand-alone sanitiser and whether it controls viruses.

PB is approved as an algaecide in the US, and is used in more than 600,000 private US pools. It is marketed in Europe by Pristine Pools Limited (PPL) and was launched in the UK and France earlier this year (2006).

One reason for the uncertainty over its value as a stand-alone sanitiser is the apparent inconsistencies
between information issued by PPL (Pristine Pools Limited, UK) to pool users in Europe and that given by Earth Science Laboratories (ESL), when marketing it as Earthtec to US drinking water suppliers. PPL promotes PB as a ‘chlorine-free alternative’. But ESL says that Earthtec, which shares PB’s EPA registration number — 64962 — ‘enhances the efficiency of chlorine’.
....
Doubts about the suitability of PB as a bactericide were further reinforced when in June, the New York State pesticide database said PB/Earthtec could be used in hot tubs, spas, swimming pools and potable water but only as an algaecide.

I tried to access the official EU distributors website (pristineblue.co.uk) but the site no longer exists and returns a message of *** This registration has been SUSPENDED. ***! I'll try to get some local feedback, but I have this uneasy feeling about PB all of a sudden.

[BilliBob]

We almost tried it out last year. I think I'll wait till these problems clear.

One observation - Pristine Blue is 2 or 3 times the price of granular chlorine her. It is sold as a luxury advanced chlorine alternative.

[Me...]

Early morning on a poorly lit laptop in motel room drinking my first coffee so i can hardly read LOL. Richard, as usual your post has tons of info in it. 2 things though. That article refers to German Din standard and their numbers refer to a pool that has had 100% of the water heavily Ozonated and chlorinated and then de-ozonated and de-chlorinated. Then pretty much trace amounts of both are added to the return water. I think they test for Ozone 4" off the water and allow up to .4ppm.

But of course I have not read the standard in a long time either so i should say I think they used to do this. Good idea though and worked well. We seem to think we have so much water over here we can still throw it away.

Now to continue waking up ...............................

[Guest]

There are only 3 EPA DIS/TSS-12 approved disinfectants: chlorine, bromine and biguanide/PHMB/Baqua. In addition, it appears that silver ion used in conjunction with higher levels of non-chlorine shock (monopersulfate, MPS) are approved, but only at high spa temperatures (i.e. not for pools).

I looked for the documentation on these chemicals at the EPA site but was only able to find the DIS/TSS-12 standard and not which chemicals it has been awarded to.

Could you please point me in the right direction