Safe swimming with elevated chlorine

[PoolDoc]

. . . continued from above

The other articles were much less informative, and mostly contained 'me-too' recitations of the standard pool industry wisdom. Most of what I say was correct. However, the specific chlorine level guidelines listed were either unsupported, or based on WAG's (Wild A## Guesses). Apparently so was the original (circa 1970) EPA standard of 3 ppm, according to reports I've gotten from people who were sitting at that table. What was reported to me was that they based their decision on the fact that most public pools, then using gas chlorine injected into pool water containing no stabilizer, were struggling to maintain 1 ppm, but that those that did were mostly achieving what was then perceived to be adequate sanitation. The 3 ppm level was reportedly chosen as been sufficiently greater than the common 1 ppm, to offer an adequate range of operation. The problem was that this 3 ppm standard is NOT appropriate for the stabilized pool operations that was just beginning to be widespread at that time.


By the way, I found one very informative analysis posted on the web, in checking out some things for this post. In particular, it may be right up Waterbear's alley. Here's where I found it: http://almashriq.hiof.no/lebanon/600...ar-water/idrc/

That's all for now . . .

Ben
"PoolDoc"

[waterbear]

By the way, I found one very informative analysis posted on the web, in checking out some things for this post. In particular, it may be right up Waterbear's alley. Here's where I found it: http://almashriq.hiof.no/lebanon/600...ar-water/idrc/

That's all for now . . .

Ben
"PoolDoc"

Very intersting reading. The germacidal properties of sunlight and UV are well known. The most pertinent things I got from the paper are some things that we already know....Sunlight (mostly UVB) destroys simple halogens and might also destroy combined ones. Interesting side note, As I've said before I've kept aquariums for many years and when choramines became commen in drinking water treatement to prevent the formation of trihalomethanes it became a real pain in the a** to treat the water to get rid of the chloramines and the chorine. When chlorine by itself was used it only took a bit of sodium thiosulfate to destroy the chlorine and make the water safe for the tank. When chloramines were in the water we had to resort to breakpoint chlorination first and then thiosulfate....or as an alternative, it was determined that leaving the water exposed to direct sunlight for a day or two would destroy most of the choramines. OTO was the recommened test to determine when the chlorine was gone in either method. Not sure who came up with the sunlight method but it was pretty popular in my circle in the late 70's. It was discussed at the Marine Aquaruim Society that I belonged to at meetings.

Getting back to the article. From my understanding it's main thrust was what they call the 'Halisol" method which uses halogen compounds and then UVB from sunlight which continue the sanitation and also destroy the halogens and possibly the combined halogens that form.. It would then seem to support what Ben said about outdoor pools. The bad stuff gets burned off by the sun (along with the good chlorine). To carry it one step further, if one is concerned about the health effects of chlorine in their pool then adding a UV unit could reduce the levels and also have a germicidal effect. Pretty much the claims made for UV units. Downside is the destruction of the necessary residual sanitizer.

I found the wavelengths that were effective intersting....once again from my experiences with aquariums. UV units for aquariums usually peak about 280 angstroms... UVC/UVB light. I have used them and gave up on them. Never really saw any benifits. The article stated that most of the UV that came from through the atmosphere was in the 320 -400 range...UVA. Marine aquariums use a type of bulb known as an 'actinic' bulb which produces light in the 440 angstrom range but also produces a lot of light in the UVA range and many aquariums also use metal halide bulbs which produce a lot of UVB/UVA light. I have seen higher redox readings on aquariums with this type of lighting (used in reef tanks) than with standard lightling. However, algae thrives under this type of light but cyanobacteria do not. Don't really understand enough of what is going on chemically to explain it except that higher redox in an aqauarium promotes more green (good) algae and destroys red and bluegeen (bad) algae. Then again, the first type of algae that usually takes hold in a pool is green algae. I suspect this is connected to the redox potential of the water. As water quality deteriorates the redox potential lowers so green algae will appear when there is not enought FC to to kill it but there are still some oxidative processes going on (such as a pool with high CYA and 'normal' FC levels...sound familiar?). As these lessen the mustard and black algaes (related to the bluegeen algaes in tanks) take hold ( Usually when a pool has been neglected and there is no chlorine or the CYA levels have gotten sky high). Pure speculaton on my part...but food for thought!

Sorry I can't relate more of this to pools but I have a lot more experience with aquariums and the effects of lighting (and we try and get rid of halogens in the water before we put the livestock in!) However, oxidation is an important process in an aquarium and redox is an important measurement. We use UV, ozone, and even hydrogen peroxide to treat the water to oxidize ammonia compounds and organics, then rely on nitrifying bacteria to convert what is left to nitrates, and finally, on anerobic denitrifying bacteria to convert the nitrates back into nitrogen gas so it can leave the water. If the organics cannot be sufficienly oxidized first then the nitrate levels get very high and denitrification is not sufficient to keep the nitrate levels down.

One needs to understand that there is a difference between oxidation and disinfection. Oxidation occurs in an aquarium but many bacteria and algae thrive. This is why oxidation by itself is not adequite for a pool and, personally, makes me a bit suspect of relying on ORP controllers to determine proper sanitation levels. I am the first to admit that I don't know much about their application in pools firsthand but I do know that such chemicals as hydrogen peroxde, CYA, Oxone (MPS), and sodium percarbonate mess up ORP readings in pools (and test as TC on OTO and DPD tests). In fact, sodium percarbonate is no longer used as a non chlorine 'shock' for this very reason, since it was mainly used in commercial pools with ORP controllers (although it is sometimes pushed as a way to convert a biguinide pool to chlorine quickly).

I realized that is seems that I have drifted off topic but I really haven't. Disinfection is necessary in a pool. Chlorine is the best disinfectant that we have. Many of the studies on pool disinfection are based on ORP readings of 650 mv or higher to determine proper sanitation levels but there seems to be a general fallacy in this since many factors can influance the ORP reading but don't really have an impact on actual sanitation and kill times. I personally would be more concerend about the health effects of low chlorine levels than I would about higher ones! As far as how much chlorine is safe....I don't think anyone really knows from what I have been able to research. It all seems rather arbitrary. Even the selection of 650 mv for ORP readings is an aribitrary selection. Florida requires an even higher reading (I believe it is 850 mv, gonna have to check the CPO text at work).

[medvampire]

Evan
I think one of the reasons for the green algae growth under these lighting conditions is the refraction and absorbance of light in a liquid (water) as well as the refraction in the cell membrane. Particulate matter with in the water may also effect the transition of light with in the body of water.


As for chlorine’s health effects, I feel that inhalation is the greatest cause for concern (Pool doc has already coverd that one). The skin, being a selective membrane, can tolerate high levels of many materials depending on the transport material it is in. Our skin is selective in non isotonic solutions with exceptions that should not occur in a normal pool environment. I would have a greater concern if your pool is salted to an isotonic state.
Solutions that could cause posing through the skin usually cause cell damage and prevent more absorbance through the body in general. The toxins that do manage to cross the epidermal layer are usually long term toxins causing general damage to the DNA.
Before I get nailed I am speaking of the chemistry found in the normal residential pool setting.
I would much rather deal with the few free radicals I may encounter in the pool with the right chlorine balance than deal with the microbe nastiness you will encounter with out it.
Steve

[ShelleyAnn]

I just want you guys to know, I am watching this thread very closely, as I seem to be shocking (15-16ppm) more than not shocking these days due to the endless rain we've been having. Unless I get IN the pool to brush the sides it's not going to get done as I don't have the arm strength to brush the sides of our AGP from the outside.

Keep the facts/best guesses coming. Fascinating.

[waterbear]

Evan
I think one of the reasons for the green algae growth under these lighting conditions is the refraction and absorbance of light in a liquid (water) as well as the refraction in the cell membrane. Particulate matter with in the water may also effect the transition of light with in the body of water.
Actually, the type of algae that grows in a marine aquarium is directly related to the redox potential of the water! This has been documented time and again with ORP meters. With lower ORP readings there is predominently red and blue green algae growth (cyanobacteria) and brown and green algae disappear. As the redox potential rises the red and blue green disappear and brown algae forms (I believe it is related to the Mustard algae in our pools) and finally, as the redox potential rises up to about 450mv the brown disappears and green algae is the predominent form seen.

As for chlorine’s health effects, I feel that inhalation is the greatest cause for concern (Pool doc has already coverd that one).
And this is primarily a concern of indoor pools.
The skin, being a selective membrane, can tolerate high levels of many materials depending on the transport material it is in. Our skin is selective in non isotonic solutions with exceptions that should not occur in a normal pool environment. I would have a greater concern if your pool is salted to an isotonic state.
Such as the salinity found in a salt water pool with about 3000 ppm NaCl? Interesting. I believe this is still below the isotonic point but not sure how much.
Solutions that could cause posing through the skin usually cause cell damage and prevent more absorbance through the body in general. The toxins that do manage to cross the epidermal layer are usually long term toxins causing general damage to the DNA.
Before I get nailed I am speaking of the chemistry found in the normal residential pool setting.
I would much rather deal with the few free radicals I may encounter in the pool with the right chlorine balance than deal with the microbe nastiness you will encounter with out it.
Steve

On your last point I agree wholeheartedly 100%!

[CarlD]

You all have me scared! I'm gonna hide under the bed...no, wait, there's dust and OTHER inhalable particles there....

It's all about balancing and weighing risk. I prefer the risks of chlorine to the risks of water-borne diseases, viruses and other infections.

[VOLDADDY]

I'm not trying to bring politics into this thread, but this sure sounds like something Al Gore would come up with. Global warming and chlorinated pools will be the downfall of us all. Oh well, at least we can stay cooled off in the chlorinated pool until we are done in.

[CarlD]

I'm not trying to bring politics into this thread, but this sure sounds like something Al Gore would come up with. Global warming and chlorinated pools will be the downfall of us all. Oh well, at least we can stay cooled off in the chlorinated pool until we are done in.

Then don't bring politics into it. This is a discussion, in this thread, of measurable evidence and the interpretation thereof, not politically correct left or right check-list positions. Science is science, no matter how the political winds try to bend it to their position.

[medvampire]

Waterbear

Such as the salinity found in a salt water pool with about 3000 ppm NaCl? Interesting. I believe this is still below the isotonic point but not sure how much.

Well below isotonic. Isotonic would be around 9000 ppm if I am doing the math right.

Actually, the type of algae that grows in a marine aquarium is directly related to the redox potential of the water! This has been documented time and again with ORP meters. With lower ORP readings there is predominently red and blue green algae growth (cyanobacteria) and brown and green algae disappear. As the redox potential rises the red and blue green disappear and brown algae forms (I believe it is related to the Mustard algae in our pools) and finally, as the redox potential rises up to about 450mv the brown disappears and green algae is the predominent form seen.

So each has its best tolerance of oxydation in the cell membrane as well as the mitochondrial protien formation. I am still reading on the effects of chlorine on celluar structures. I have found a lot of material I still have to read. Yes, I do need to get a life

CarlD
How is the view from under the bed? Enjoyng the dust bunnies? Had to go to L.A. last year and seen some bunnies I would love to get under the bed with.

I just cant understand why some one would want to swim in a pool of filth. The pros here spell out the needed levels of chems in a system that works in daily use and theroy. The methods here are easy to follow and help is your keyboard away. I understand this method is not what the pool stores tell you but this method works.
Steve

[waterbear]

I just cant understand why some one would want to swim in a pool of filth. The pros here spell out the needed levels of chems in a system that works in daily use and theroy. The methods here are easy to follow and help is your keyboard away. I understand this method is not what the pool stores tell you but this method works.
Steve

Some pool stores DO use this method! (but we do it with liquid chlorine, alk increaser, and Proteam "Supreme" instead of bleach, baking soda, and borax. Something has to pay my salery!
(and we sell the liquid chlorne at $3.69 for a 2.5 gal refill of 12.5%...cheaper than the ultra bleach we sell....we're a large hardware store with a large and complete pool dept. Everything from chems to equipment and even AG pools!)