Errors in Swimming Pool Guidelines
You've heard the story of the emperor's new clothes? You know, the fairy tale streaker?
That's the archetypal TEKTAT. Everybody knew the emperor wore clothes, at least in public. And so, in spite of all the evidence, they convinced themselves that all that wobbling flesh they saw was merely proof they needed new glasses.
Oh . . . TEKTAT? Things Everybody Knows That Aren't True.
The swimming pool business is full of TEKTAT's. Unfortunately, many of these TEKTATS are in the information that you -- the swimming pool owner -- receives in guidelines and booklets from the pool industry.
Some of these things ARE true, some of the time, but none of them are true as much of the time as the swimming pool industry claims. For example, sand in swimming pool filters DOES sometimes need to be replaced -- but not simply because it's been in the filter for a long time. If it's gummed up, with Baquacil or Softswim, replace it! If it's solidified with calcium, replace it! But if the wrong size of sand was used, replace it! But if it's just old, and has nothing visible wrong with it, leave it alone!
Anyhow, on to the TEKTAT's
The last two really bug me. Why?
Probably the greatest chemical destruction I see at the large commercial pools results from the fumes of muriatic acid used to control pH. I've literally seen over $100,000 of damage at just one pool. Much of this comes from attempting to follow the dictates of the pool industry TEKTAT: "if you use bleach, you must use lots of acid."
BS! (Barnyard Slush)
Just to keep it short, For years, I managed a 300,000 gallon pool this summer with less than 5 gallons of acid . . . while using hundreds of gallons of bleach!
But the high pH/eye irritation TEKTAT comes directly from people who should know better. For example, in the National Spa and Pool Institute's VERY expensive manual, Basic Pool and Spa Technology, by Diane S. Rennell, Ph. D. (c)1989, on page 244 we learn that pH levels above 7.6, cause "eye discomfort". You can find the same stuff on page 38 of the NSPF's Certified Pool Operator manual, and in many other places. A typical web page that reproduces this TEKTAT can be found at New York University's "ScienceOnline" site* .
But is it true?
The grandfather of swimming pool eye irritation studies, a study of Yale University swimmers by Dr. Eric Mood, published in 1951 actually shows that eye irritation is lower at pH 8 than at pH 7. Later studies show that chlorine, chloramines, salinity all play a role in determining eye irritation.
My experience? The antique CDC Swimming Pool manual (HHS pub 83-8319 - 1976), page 66, seems about right when it identifies pH 8.0 as the least irritating level!
*(In fact, this page
-
http://scienceline.org/2007/07/ask-bewley-cloudypooleyes/ -
is FULL of errors & distortions -- many aren't even
TEKTATS; they're just dumb:
This whole page from a seemingly reliable source is an example of what happens when non-expert journalists write articles about things of which they are completely ignorant! Unfortunately, the majority of articles on the Internet about pools and pool chemistry are written just that way.)
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