Best Guess Table

[PoolDoc]

It may interest some of you to know that one of the forum members, Richard F. (not his forum ID), who has both a strong interest in this topic, and a degree in chemistry, has been investigating it rather intensively over the past year or so. Many of the results he's achieved are extremely technical, but it now looks like we may be able to use some of his work to update the Best Guess Table, early next season.

Ironically, it now looks like the primary changes will be to INCREASE the shock dosages, which are low, if you look at the theoretical HOCl levels achieved. I need to do some liner testing with those high levels before I make those change, however.

Also, please keep in mind, that what I was trying to accomplish with the BGT was a "works for almost everybody / is safe for almost everybody" guide. Inherently, this means creating a guide that is NOT perfectly optimized for each pool, but rather one that is GOOD ENOUGH for almost all pools.

There are several issues to keep in mind.

First, prudent operational conservatism requires the biggest safety margins be maintained adjacent to high risk boundaries, rather than low risk bondaries. Overdosing with chlorine approaches a low risk boundary: the consequences of doing with 6 ppm instead of 3 ppm are almost always trivial. But underdosing with chlorine approaches a high risk boundary. The consequences of maintaining 1 ppm instead of 2 ppm, can be an expensive (in time, money, chemicals and 'stress') episode of algae. It can also result in infection. Consequently, prudent analysis will lead to operational guidelines that err in the direction of overdosing more frequently than in the direction of underdosing.

Second, it is also operational prudent to consider common forms of operator failure, and to set up guidelines, where possible, that minimize the consequences of such failures. With pools, whether home or commercial, 'missed dosing' represents one of the most common forms of operator failure. One possible solution is the use of a feeder. In the past, I've recommended the Rainbow RB-320 as a functional feeder with tolerable 'negatives'. More recently, I've concluded that SWG's are a superior alternative, for those who can afford them. But, high Cl / high CYA represents an operational alternative that is accessible to virtually everyone.

With respect to both issues identified above, I think what I've done, and recommended, largely 'gets it right'. (For this reason, I'd prefer to see less 'how to optimize for low chlorine use' discussion in the general forum sections. I think such discussions tend to lead to pool failure episodes for newbies. Here, in the China Shop, it's fine.)

But, there's a third issue, that of anti-chlorine paranoia. This fear distorts people's perceptions of where the real risks are, causing many (even some of you, apparently) to place a value on low chlorine levels that, in my opinion, is contrary the value that would be attributed as a result of any real systematic analysis of the relative risks and benefits. I've just realized -- actually, when I was posting on the chlorine paranoia yesterday -- that I have not adequately communicated anywhere on my site the information people need to help them make that analysis, at either a 'popular' or a technical level. This is something I need to fix. I'll try to do so this winter.

Meanwhile, I'd encourage some of you to consider what sort of weight should be placed on the benefits of low chlorine (possible reduced costs; reduced suit / liner fading; possible reduced risk of long term effects) versus the costs (low margin of error; increased risk of algae; increased risk of acute infections; increased complication of care guides). I tend to believe that the only substantial realized benefit to optimized low chlorine is what might be called 'tinkerer's satisfaction'. By this, I mean the satisfaction gained by someone who tunes up their PC, and then runs a test to validate that it now benchmarks at 18,700 whatevers instead of the 16,980 whatevers it was running before. The functional benefit of this sort of improvement is virtually nil, but the psychic satisfaction is high.

Please understand that I see nothing wrong with pursuing 'tinkerer's satisfaction': I've done so many times myself. But, the reality is such optimization is NOT what most newbies here need. Instead, they need help in achieving 'good-enough', reliable, and trouble free operation. They can (as some of you have) learn to 'tinker' later, once they've gotten the basics down.

I'd ask all of y'all here to consider adopting such a point of view, when you post in the general forum . . . for the sake of people who just want their pool to work.

Thanks,

Ben Powell
"PoolDoc"