Copper silver systems and proper pool sanitizing

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Copper silver systems and proper pool sanitizing

Postby Larry » Wed 11 Mar, 2009 13:18

The following was originally posted here by chem geek (Richard) on 06 May 2008:

There does not appear to be a lot of data on the kill times for copper and silver in water because they are relatively long by themselves. Most sources (CDC, etc.) just refer to "slow disinfection". For a scientific example, this link describes a 6-log reduction (99.9999% kill) in Legionella pneumophila at a copper concentration of 0.1 ppm taking 2.5 hours. For comparison, 1 ppm Free Chlorine (FC) without CYA would accomplish the same kill rate (for most heterotrophic bacteria) in around 15 seconds while normal FC/CYA ratios (FC level being 10% of CYA level) would accomplish the 6-log kill in around 5 minutes.

Most bacteria reproduce at rates, under ideal conditions, of doubling every 15 minutes to an hour (see this link). So a disinfectant that prevented runaway bacterial growth would need to kill bacteria faster than they can reproduce. A doubling is equivalent in rate to being balanced by a 0.3-log (50% kill) reduction. The 2.5 hour 6-log reduction is roughly equivalent to around 7.5 minutes of a 50% kill. This is why copper and silver can prevent runaway bacterial growth. They generally kill bacteria faster than they can reproduce, though not by a huge margin.

In other words, copper and silver are good as surfaces that prevent bacterial growth, but aren't so good at killing existing bacteria populations at a fast rate. So given enough time and no new introduction of bacteria, silver/copper disinfection would be sufficient. However, bacteria are constantly being introduced into the pool, most especially by bathers. Therefore, copper/silver alone are not sufficient to prevent the transmission of disease (bacteria, viruses, protozoa) from person-to-person. This is the main reason such systems are never used alone in public pools. If they are used at all, it is in conjunction with at least small amounts of chlorine.

Also, copper and silver are not very effective at inactivating viruses at low concentrations because viruses don't grow in water -- they need a host to reproduce. They are also not effective against protozoan oocysts (e.g. Giardia or Cryptosporidium) but chlorine isn't very effective against these oocysts either (chlorine is especially ineffective against Crypto) though chlorine is effective at inactivating viruses. A scientific paper describing copper inactivation of viruses is here where you can see that to achieve 2-log (99% kill) reductions in viruses in under 30 minutes it required concentrations on the order of 10-1000 ppm which is far higher than found in pools. The virus inactivation time for the copper levels normally used in pools would be on the order of days, assuming this is scalable.

As for algae, copper kills algae quite a bit faster than it can reproduce since algae generation (doubling) times are in the 3-8 hour range. In fact, some algaecides use copper for this purpose.

There is simply a spectrum of risk with regard to the type of disinfectant that you use. Not having an EPA-approved sanitizer (chlorine, bromine, Biguanide/Baqua/PHMB) simply means the risk is higher, but it does not mean that your water is teaming with bacteria. If you were to have someone who was sick be in your pool, they could transmit their disease to you (including the fecal-to-oral route). Also, some bacteria can form biofilms and be more resistant to disinfection so that a more powerful disinfectant is required (or an enzyme or oxidizer specifically able to break down biofilms).


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Copper silver systems and proper pool sanitizing

Postby Aquaclear-NZ » Sat 29 Aug, 2009 18:48

so in short - what yo uare saying is that copper and silver ionisation systems should be run with normal levels of chlorine....

this seems to clash slightly with your advise on the pool wizard website
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Copper silver systems and proper pool sanitizing

Postby Me... » Sun 30 Aug, 2009 10:03

The copper/silver systems target bacteria and algae. There are many more tasks to be dealt with in the water. Chlorine pretty much covers all the bases leaving it as the #1 choice for a residual sanitizer. Everything else is going to require something else. There is nothing else, SAFE, that you can add to your pool that will kill algae, kill bacteria and oxidize byproducts and organics.

So while many of these other products can be beneficial and helpful, they cannot do the job they need to do by themselves.
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Copper silver systems and proper pool sanitizing

Postby Medical Man » Mon 20 Sep, 2010 20:34

Being in the health industry and knowing what adverse health issues are associated with Chlorine, I prefer to take my chances with mineral products to treat my water. I have been a pool/spa owner for over 20 years and never had an issue with bacterial infections while using mineral products. I have filtration systems to remove the chlorine from the water I drink and have a system that removes it from my shower. I do this for a very good reason, and it's for my health.

The so called experts on here can tout Chlorine use all they want but when it comes to your health you should investigate what soaking and breathing in chlorine fumes can do to your health. Here's an exert from an article regarding Chlorine, this is one of many ...

In 1964, the World Health Organization estimated that 80% of all cancers are due to synthetic carcinogens. One group of dangerous chemicals, organochlorines, is a class of industrial agents made of chlorine and carbon. The combination is basically indestructible making it an ideal medium for industry.

Organochlorines do not occur in nature. They are used to manufacture plastic and pesticides. The end products, the by-products, and the production process all expose humans to organochlorines. Paper, for example. Pulp and paper industries use chlorine bleaches to whiten paper. The process of bleaching (chlorine) paper (carbon) releases dioxin, one of the most deadly substances on earth. According to Greenpeace, there is no such thing as a safe level of dioxin.

Mounting evidence suggests that organochlorines are persistent in the environment and in the human body. They are bio-accumulative, increasing in toxicity and magnitude as they move up the food chain. WHAT DO YOU THINK SOAKING IN YOUR SPA BREATHING AND SOAKING IN CHLORINE DOES TO YOU BODY?

Greenpeace released a comprehensive report in 1993 entitled Chlorine, Human Health and the Environment: the Breast Cancer Warning. Cited are 177 organochlorines found in tissues of human and animals: 177 that simply did not exist 50 years ago.

Women's bodies are particularly vulnerable to organochlorines because these chemicals accumulate in fatty cells in the breast and because they mimic estrogen causing abnormal cell reproduction.

Profit Motive
Could it be a cover up? Read the label on a bottle of bleach and tell me what you think?

"To fully understand the big picture," says WHAN's Maia Syfers, "you have to come from the point of view that we live in a free enterprise, profit-oriented society."

First manufactured around the turn of the century, organochlorine production escalated during World War II. When the war ended, chemical companies turned to the domestic market. During the 50s, 60s, and 70s, Dow Chemical, Imperial Chemical Industries (ICI, to Europe what Dow is the US), Occidental Chemical and the like made millions.

When scientists started making connections between cancer and chemicalization in the early 60s, the industry rebuffed environmental regulations placing profitability above all else. As our health industry is moving closer to a for-profit model, so has the cancer establishment. For the full article click the link below or copy and paste it in your URL.

I can't believe people arguing over the safety of Chlorine and the advantages using it has over mineral products because it's EPA approved and it has faster kill rates ... do those faster kill rates include us humans?
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Copper silver systems and proper pool sanitizing

Postby chem geek » Tue 21 Sep, 2010 00:55

See my response here in another thread where you also posted.

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