So how come there aren't a LOT of sick people?

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Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 0 ppm . . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
=> 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
=> 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
=> 100 - 200 ppm . . . 8 ppm . . . . . 15 ppm . . .. 25 ppm

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According to the pool store computer (Bioguard) the 'ideal' level for CYA is 30-200ppm and for Chlorine is 1-3ppm. But according to the best guess chart, anything above 30ppm CYA is not sanitized if chlorine stays at 1-3ppm? If so, how come there aren't a lot of people getting sick in their pools? Wouldn't there be lawsuits galore?

Where did these 'best guess' numbers come from, and how come they are so far off from 'the industry' standards?

Inquiring minds want to know... :p

Ever swim in a nasty pond, lake or river? The human body is pretty resiliant.

** Just kidding, although I am sure that is part of the answer. When I first found that chart I was thinking the same thing.

Maybe there are not many sick people but there are sure a lot of sick pools. Look at all the posts about algae and green pools. This is were most of the problems occur because of mismatched CYA and CL.

Have you seen the way they've been voting lately?

Before I found this site, I followed that 1-3ppm no matter the CYA, I live in Mass. and in May/June the water was pristine crystal clear because the water temp was in the 60's/70's and then when the water started to warm up in July then the algae started. Water never turned green, just all over the liner, in the filter, even the clear view to see the backwash had green in it. I didn't understand what I was doing wrong. I was using gallon after gallon of Algaecide, still green. Then I found the chart on this site and 3 years later and have never had algae again. I use pucks to chlorinate in a floater, bleach to shock and have switched to Baking Soda and Borax.

This makes no sense to me......

I thought the reason concluded behind SWG companies all suggesting 80ppm CYA was that you could maintain a lower chlorine level.

Does this chart state that SWG owners need at lease 5ppm Chlorine to have a safe pool? I dont think my SWG will generate that much.

My understanding is that it's different for SWG pools, as the cells are basically super chlorinating the water continously (as long as they're running), so less of a residual is needed in the pool.

http://www.ppoa.org/pdfs/PrP_Cyanuri...0or%20Bomb.pdf

it makes for an informative read . And even if I never read anything about CYA, I know whats working in MY pool. Before I found this site , I couldnt figure out why my pool was such a pita. When I learnt to deal with the high cya , the pool looks great , less work and more fun. dont need to prove anything else to me

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Originally Posted by Tredge

This makes no sense to me......

I thought the reason concluded behind SWG companies all suggesting 80ppm CYA was that you could maintain a lower chlorine level.

Does this chart state that SWG owners need at lease 5ppm Chlorine to have a safe pool? I dont think my SWG will generate that much.

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SWGs are different. See this thread:

http://www.poolforum.com/pf2/showthread.php?t=3185

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Originally Posted by CToon

http://www.ppoa.org/pdfs/PrP_Cyanuri...0or%20Bomb.pdf

it makes for an informative read . And even if I never read anything about CYA, I know whats working in MY pool. Before I found this site , I couldnt figure out why my pool was such a pita. When I learnt to deal with the high cya , the pool looks great , less work and more fun. dont need to prove anything else to me

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Great article, thanks!

I use the liquid bleach regimin too after visiting this site, and I also have great results. Just trying to understand a bit more of the why. :D

TW

I work in a hospital laboratory and see peps that are sick from pools. The reason you don’t hear about it is because the environmental source of infections are hard to identify. I would venture most middle and outer ear, eye infections, and wound infections in families with pools are pool related. I have seen skin infections caused by Pseudomonas from pools. I have seen respiratory infections form pools and spas. I read an article a few days ago about pathogenic E.Coli transmitted by pool water. Its there you just don’t hear of it very much. I feel that if you are seeing algae you have a higher risk from pathogens in the pool as well. If our immune systems are functioning well we can fight off mild attacks but in the young and elderly populations are at higher risk.
Steve

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Originally Posted by medvampire

The reason you don’t hear about it is because the environmental source of infections are hard to identify. I would venture most middle and outer ear, eye infections, and wound infections in families with pools are pool related....

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Makes sense. Though I'm no doctor or even in the medical field, that is essentially what I've always suspected.

Dave

Since folks are stating their credentials fwiw (for what it's worth), I'm an RN BSN (LLU), with a PHN certificate. I worked as an RN for over 20 years, received a graduate degree in engineering and moved along.

The CDC (Center for Disease Control), started tracking WBDO (Waterborne Disease Outbreaks) associated with RW (Recreational Water) in 1978 so that's as far back as their statistics go. The latest surveillance summary I've seen is dated 2002. You can read it here:

http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5308a1.htm

Next CDC only tracks clusters and reporting is voluntary the above is an interesting read and gives you a window into RWI (Recreational Water Illness). Since this leaves out the large population of RW, private swimming pools and individuals owners/swimmers you can surmise that this is simply the tip of the iceberg.

While I wouldn't go quite as far as MedVampire does

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Originally Posted by medvampire

I would venture most middle and outer ear, eye infections, and wound infections in families with pools are pool related.

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I'd say he's pretty close. The only reason I don't completely agree is the large groups of pink eye (infectious conjuctivitis), uri's, impetigo, scabies, tineas, pediculosis and diarrheal illnesses amongst the pre and elementary school population.

It's very important to remember drowning is also an RWI and probably the easiest preventable one.
Jo

Jo
I do agree with you most of these illnesses are common in close order groups for example school and day care settings I was referring to environmental sources or infections of unknown origin. I should have been more specific about the source and epidemiology of the infection but I trying to keep as general as possible.
I do agree that drowning is the greatest cause if disability and death from pools and the most preventable one.
Steve

The dangers of DHMO once again!

Waterbear

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The dangers of DHMO once again!

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Think we will get mod slapped if we start this up again?:D
Steve

It's not that SWGs are "different", it's that when running properly they have two advantages over other chlorination systems:
1) They are constantly gen'ing chlorine at low levels. You don't actually need a lot of chlorine to keep your pool sanitary, but it has to be able to respond to demands on it--like people and suntan oils, etc. A residual level gives you a safe lee-way or metabolizing stuff will drop you below that sanitary level, leaving your water vulnerable to contamination. But an SWG takes over for that
2) They super-chlorinate the water that passes through them, killing everything in it.

Remember: SWGs ARE chlorine systems and follow chlorination rules. But rules of thumb may not be as applicable.

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Originally Posted by CarlD

It's not that SWGs are "different", it's that when running properly they have two advantages over other chlorination systems:
1) They are constantly gen'ing chlorine at low levels. You don't actually need a lot of chlorine to keep your pool sanitary, but it has to be able to respond to demands on it--like people and suntan oils, etc. A residual level gives you a safe lee-way or metabolizing stuff will drop you below that sanitary level, leaving your water vulnerable to contamination. But an SWG takes over for that
2) They super-chlorinate the water that passes through them, killing everything in it.

Remember: SWGs ARE chlorine systems and follow chlorination rules. But rules of thumb may not be as applicable.

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I've read the threads and the very informative PDF link on CYA....I'm trying to understand.

If SWG's constantly generate new chlorine then there should be less need for CYA not more!

They way I understand it CYA acts as a time release but the tradeoff is that the chlorine isnt as "active". I understand the value of that tradeoff if I were adding chlorine once a day but a SWG adds all day and night.

I also understand that a SWG superchlorinates at the cell and in the pipes...but high CYA has nothing to do with chlorine in the pipes, its intended for keeping chlorine in the pool longer (Protection from sunlight esp)

I'm sure SWG's opperate safely at these CYA levels...I guess I just cant get my mind around the science behind it.

The part of that PDF article that got my interest is this chart:

http://i18.photobucket.com/albums/b1.../pools/cya.jpg

He suggests that 5-12ppm is good for an automated pool, no more than 20ppm for a manually managed pool.

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Originally Posted by Tredge

If SWG's constantly generate new chlorine then there should be less need for CYA not more!

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Actually you need more! The cell instantaneously generates a high concentration of chlorine that destroys the chloramines AT the cell.

If there was not a high CYA level, most of it would be used up before it got into the pool proper. The alternative would be to run at high chlorinating outputs, resulting in rapid reduction of cell life.

Hope this helps.

Pat

Tredge, I don't get the feel that SWG owners are operating their units 24/7, and as such need the CYA to keep the residual when the unit's off.

My SWG manufacturer recommends 24/7 but they could be unique.

I'm just hearing conflicting things and the technical evidence in this thread supports a lower CYA....especially for SWG systems.

I understand a high CYA can extend the Cell life because you can maintain a lower chlorine ppm at a lower setting, but does that really mean a healthier pool?

Would it be incorrect to say that a SWG system running at 0 CYA and 1ppm chlorine 24/7 is the most effective? (Not taking cell life into account).

I dont want to contradict this forum, perhaps a new thread in the "china shop" is more appropriate?

If you run a SWG 24/7 does that mean the main pool pump is also running 24/7?

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Originally Posted by aquarium

If you run a SWG 24/7 does that mean the main pool pump is also running 24/7?

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No it runs on its own or with the filter running. It has its own pump that is capable of pulling water through the filter.....although not nearly as fast of course.

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Originally Posted by Tredge

My SWG manufacturer recommends 24/7 but they could be unique.

I'm just hearing conflicting things and the technical evidence in this thread supports a lower CYA....especially for SWG systems.

I understand a high CYA can extend the Cell life because you can maintain a lower chlorine ppm at a lower setting, but does that really mean a healthier pool?

You use whatever setting YOUR pool needs to be healthy. It will depend on bather load, weather, and any other kind of upsets. The lower the setting you can use on the pool the better.

Would it be incorrect to say that a SWG system running at 0 CYA and 1ppm chlorine 24/7 is the most effective? (Not taking cell life into account).

Yes it would be incorrect. Please reread what I said in my post above. You need the CYA ppm for the reasons stated.

I dont want to contradict this forum, perhaps a new thread in the "china shop" is more appropriate?

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Hope this helps.

Pat

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Originally Posted by PatL34

Actually you need more! The cell instantaneously generates a high concentration of chlorine that destroys the chloramines AT the cell.

If there was not a high CYA level, most of it would be used up before it got into the pool proper. The alternative would be to run at high chlorinating outputs, resulting in rapid reduction of cell life.

Hope this helps.

Pat

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:lightbulb lighting over head:

Thanks, Pat. This is about the 10th time I read that if there was not a high CYA level, most of the SWG-produced chlorine in the cell would be used up before it got into the pool proper - and I finally figured it out -

Without the added CYA, the superchlorination at the cell is TOO effective, so, under higher bather load or organic contaminant conditions, there isn't much unused FC left after the water passes the cell and goes toward your return!

With additional CYA present (say 60-80 ppm), there is a little less superchlorination at the cell (because chlorine is less effective per PPM with CYA present), so there is more residual left as the chlorine passes back into the water into your pool, where it can fight contamination of the water actually in the pool and (keeping this sort of on topic), preventing people from getting sick from stuff in the pool!

Finally, because there is still effective (just a little less powerful per PPM because of the 60-80 ppm CYA) superchlorination going on in your water because the salt water generator cell is operating, you should be able to run with a (slightly) lower amount of FC residual in your SWG pool than with a pool chlorinated in batch form (like bleach or cal-hypo) or drip form (chlorine feeders, trichlor pucks) for your given level of CYA.

:)

ps - the "benefactor or bomb" article is very good but needs to be taken with a grain of salt (whether or not you are running a SWG! ;) ) PoolDoc has excellent comments elsewhere on the forum about it - here is the link. CYA is NOT "bad" -- running your pool with too much of it and not enough chlorine (like anyone using a constant amount of trichlor pucks in a feeder all year, and using a test kit or strip that only counts to 5 or 10ppm of chlorine) IS "bad". It's that simple. And for people who have very sunny pools (aylad comes to mind), CYA is a huge help. My pool isn't that sunny, but when I cholorinated exclusively with bleach last year, I chose a higher CYA rate so I could add bleach every other day instead of every day. And now that I have an SWG, I am slowly increasing my CYA from 35 to (probably) around 60.

My understanding: with the addition of common sense and real-world experience to the "benefactor or bomb" material, you get Ben's "Best Guess" chart.

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PoolDoc has excellent comments elsewhere on the forum about it - here is the link.

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Thanks for linking that. Ben does an excellent job as usual responding to that article.

The folks in this forum are really impressive.

Been following this thread and need to add a few comments. The following gets somewhat technical so you have been warned!
1. When the article on CYA is talking about automatic delivery of chlorine it is NOT talking about a SWG. It is talking about using a peristataltic pump and an ORP controller to automate the addition of liquid chlorine to a pool to maintain a certain redox potential...apples and oranges, not the same thing at all.
2. the author of this article was/is connected with a company that manufactures ORP controllers for pool and CYA messes up ORP readings. ORP controllers work best when there is no CYA present by constantly dosing the water with chlorine as it is demanded by use.
3. Let's examine a quote from the article (with empahsis added by me):
"An ORP level in water of 650
mV is the most widely accepted minimum for qualitative
results, worldwide.
650 mV of ORP can be achieved with a variety of
chemical compounds, conditions, and influences. It is “qualitative”.
650 mV is the same working value whether it takes only
.1 ppm “free” chlorine at pH 7.2 with no CYA to get there or 3
ppm at pH 8 in the presence of 30 ppm CYA to make it. In the
second of these two extreme examples it takes 30 times more
chlorine to achieve the same results. All it took was a pH elevation
and the addition of cyanuric acid."

when sodium hypochlorite is added to water it dissociates into hypochlorous acid and hypochlorite ions. Hypochlorous acid is what has the oxidizing ability...hypochlorite ions do not. The ratio of hypochlorous acid to hypochlorite ions is pH dependant. At a pH of 7.2 over 75% of the chlorine is in the form of hypochlorous acid so the oxidative ability is very high!
At a pH of 8 less than 20% of the chlorine is in the form of hypochlorous acid. It is a given that the addtion of cya will have an effect on lowering the oxidative ability somewhat since chloroisocyanurates are less potent oxidizers than hypochlorous acid. However I submit that it is the change in pH that has the most impact on this example. The differential in oxidative ablilty with just a change in pH is over 55% for a given level of residual chlorine! IF my math is correct it would take over 1.8 ppm FC at pH 8 with NO CYA to achieve the same results as .1 ppm at pH of 7.2. The addition of 30 ppm CYA only affected the results by slightly over 1 ppm (about 35% more needed) while the change in pH needed about 170% more chlorine for the same oxidative ability when no CYA is present!
Which is the parameter that has the greatest impact here....pH or CYA? I submit it is the pH!
4. The author states at the end of the artice
"This writer has, by the way, used cyanuric acid successfully
and with benefit in his own pool for years."
This certainly sounds like an endorsement for using CYA to me!

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Originally Posted by CarlD

Have you seen the way they've been voting lately?

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I love this observation.:D