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

[bradjo]

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

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

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

[medvampire]

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

[waterbear]

The dangers of DHMO once again!

[medvampire]

Waterbear

The dangers of DHMO once again!

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

[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.

[Tredge]

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.

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.

[aquarium]

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



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

[PatL34]

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

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