I do a lot of reading. The older I get – and the less time I spend in the field – the more I read all the things that I used to tell myself I would get around to reading when I wasn’t too busy cleaning pools.
And, man, oh man, am I disappointed. For most of my career I’ve just had my head down, focusing on taking care of my pools, going to the odd show here or there, attending a water chemistry seminar now and then. But most of my experience and knowledge was gained poolside. I haven’t paid a lot of attention to what The Experts write – with the exception of Bob Lowry of Lowry Consulting Group. I’ve said it elsewhere in this blog; if you passed the IPSSA water chemistry exam in the last 20 or 25 years, you probably used Mr. Lowry’s books to study for it. He writes great, layman’s explanations of what’s happening in pool and spa water. But other than his stuff and what I’ve picked up on my own from textbooks and the like, I haven’t paid a lot of attention to many of the documents that end up, through their influence, controlling the direction of our industry.
They’re not really documents, per se. You seldom, if ever, see the actual study information – like the real research data, for instance. The internet is huge and space on it is free, or next to free. But still, you never get a look at how tests were really done, or all the data that was collected. Mostly they’re just reports, or, more correctly, brochures. And the ones that seem to have the most stacked decks and the most biased information are the ones from companies selling stuff to us.
Now, if you’re a homeowner wondering what any of this has to do with how salt damaged your pool, it doesn’t. Use the Labels on the right to find blog pieces about your symptoms or about Making Salt Work for your pool, because this blog piece is going to have a huge water chemistry geek factor. But if you’re one of the guys who is in that spot that I was in until about a year ago, busy with your route and your repairs, with your head down and hardly any time to read what it is everybody says are the latest governing documents for how we ought to take care of our pools, take a minute and read this:
There’s this report that’s been rattling around the internet and the trade shows and seminars for the last several years. You can find it here:
Sorry. Dead Link
It’s title on that first website is:
High Cyanuric Acid Levels & Plaster Degradation In Swimming Pools
by Ellen M. Meyer, Ph.D
It’s commonly referred to as the Arch Study. It was a three part study; the first part 5 weeks long, the second part 6 months long, and the third part 4 months long. The gist of the first part of the study is that they put some freshly made plaster coupons into some test tanks and then added as much as 500 ppm cyanuric acid to them, and that over a period of 5 weeks, the cyanuric acid level fell from 500 ppm to about 140 ppm in one tank, and from 200 ppm to about 100 ppm in another tank, and that in both tanks, the cyanuric acid collected as a residue on the surface of the plaster. The fourth paragraph says, “surface analysis showed the accumulation of cyanuric acid on the plaster”.
Okay, so just stop. Stop right there and think for a minute. We’ve all seen pools with 200 ppm stabilizer, right? If you’re honest with yourself, unless you’re Super Poolman, you probably have a handful of pools like that on service right now. I know I do. Most of my pools are under 100. But there are some that are higher. I admit it.
Now, ask yourself a simple question; have you ever seen the cyanuric acid level in those pools drop to as low as 100 ppm and deposit as a residue on the plaster in a 5 week period?
I didn’t think so. In fact, I know so. In fact, it is safe to say – through thirty years of empirical observation - this has never happened anywhere outside the laboratories of Arch Chemicals.
So, how much stabilizer is 500 ppm? Well, it’s about 42 lbs. of stabilizer dissolved into your average 20,000 gallon pool. I’m talking pure, granular stabilizer melted into a freshly plastered backyard pool. Because that’s how this study was done. They took freshly troweled plaster coupons and put them in a tank and put in an amount equal to you putting 42 lbs of stabilizer on Day One of start-up. And how do I know that? Because I finally sat down and gave it several careful readings – something I don’t think many of us have done – and down in the 5th paragraph, in talking about pH control during the 6 month study, they say “because the plaster coupons were new, the pH rose continuously…”
Oh, yeah, that’s Real World. Throwing 42 lbs. of stabilizer into a freshly plastered pool.
So, the assumption I make about that first 5 week test was that they put these new plaster coupons into tanks and didn’t adjust the pH during the 5 week test, and viola! The pH skyrockets and the cyanuric acid falls out of solution, accumulating on the surface of the plaster. Here’s a quote from Dr. Meyer in a Pool & Spa News article: “The cyanuric acid was no longer in solution… It was on the plaster surface, having some kind of affect.”
Now, that’s not really a scathing indictment, is it? Having some kind of affect?
I promise you, if you plastered and filled a 20,000 gallon pool, and on Day One you dissolved 42 lbs. of cyanuric acid into the water, then went away for 5 weeks, when you come back, it would be a logical result to have more than half your cyanuric acid plated out on that pool’s surface.
But then, if you didn’t have any pH control for 5 weeks, you’d have to demo that plaster and start over, because a little cyanuric acid on the surface of the plaster would be the least of your problems.
So, based on these shocking results, this company - that coincidentally makes cal hypo products and owns a few non-chlorine alternative sanitizer labels - decided to do a 6 month tank test. Now they introduce water chemistry parameters. I know that because the say so, a conversation conspicuously absent from the 5 week test. They say the “water in the test tank was adjusted to try and maintain pH between 7.2 and 7.8 and alkalinity between 60 to 100 ppm”. The key phrase there is “try and maintain”. Note that it doesn’t say, like it does later when talking about the 4 month test in test pools “were maintained at…” Old “try and maintain” indicates that boat was missed. So we can assume, from the very language of the report, that, because they were using new plaster coupons, they weren’t able to maintain their own stated water chemistry parameters. You know how it is; three day weekends, somebody forgot, etc.
Too, repeat those water chemistry parameters back to yourself; 7.2 to 7.8 pH and 60 to 100 ppm alkalinity. What happened to 7.4 to 7.6 and 80 to 120? That’s industry standard, isn’t it? Then, after stating these parameters, they contradict them in the next to the last paragraph, where they admit “that pH and alkalinity of the tanks ran on the high side (pH~8, TA~90 ppm), but then they say that despite “the high pH and alkalinity in the test tank, plaster degradation was still seen.
Really? Look at the 3 photos, labeled 100 ppm, 250 ppm & 500 ppm. Those are the ones from the test tanks. Looks like scaling to me, which is exactly what you get when you run your pool water scaling on the Saturation Index.
Now, these “dramatic results” prompted them to do yet a third study; “additional tests were initiated in larger bodies of water where the water balance could be maintained more easily”. They operated five test pools, maintaining their water chemistry at 7.2 to 7.6 pH, alkalinity at 80 to 120 ppm and calcium hardness at 180 to 250.
After four months, they took pictures, which you can see at the bottom of their page. On the left, you have 14X magnified plaster coupon immersed for 4 months in 0 ppm cyanuric acid. Look hard at that photo. Doesn’t that surface look like the beginning of an etched surface? Doesn’t that look like we’ve already burned off the butter and we’re starting to expose the aggregate?
Now look at the plaster coupon on the right, the one that was in the pool with 200-250 ppm cyanuric acid. That’s looks severely etched, doesn’t it? Well, 7.2 pH, 80 ppm alkalinity and 180 ppm calcium hardness is an aggressive environment, all the way up to 80 degrees, assuming a minimum TDS of 430 (their calcium hardness and their cyanuric acid), and all the way up to 90 degrees if the TDS was a little higher, even as little as 80 points higher.
But let’s say that this was done in an air conditioned laboratory in Georgia. A reasonable assumption, right? So, let’s assume a water temperature of 72 degrees. That water is even more corrosive. An extra 0.1, and it being a logarithmic number, 0.1 is a doubling of it’s corrosiveness. Basically, that water is 5 times more corrosive than water balanced to the industry standard of 7.5 pH, 100 ppm TA, 200 minimum Calcium Hardness and average water temp of 78 degrees.
I’m using the handy automated Langelier Index provided by one of the folks who host this study on the internet. You can find it here:
Now, I have a couple of questions about this report.
1. Why did they use such low calcium levels? 180 to 250 isn’t mean calcium as recommended in our industry. When we all start up pools, we make sure the calcium is at least 200 ppm, and I’ve always been told by plaster consultants whose opinions I have come to respect that probably 250 ppm is a better place to start, that 200 ppm is the minimum. And the reason we start our calcium so low is to let the level grow over time, with condensation and the addition of calcium based chlorine products. But why run it so low in the lab? Why not set and hold all pools at 250 or 300 ppm? Because the lower calcium sure clouds the conclusion that it was cyanuric acid, and not out of balance water, that caused the etching.
2. Why is the loss of cyanuric acid only mentioned in the first 5 week study? Did the application of water chemistry parameters in the 2 subsequent tests eliminate that phenomena? Shouldn’t we be able to see the buildup that they talked about in the first test in the 5 photos from the second and third test that accompany this article? Shouldn’t there have been some mention of how they were constantly reintroducing cyanuric acid to the test tanks and test pool in the 6 month and 4 month studies? Remember that quote from Dr. Meyer in a Pool & Spa News article: “The cyanuric acid was no longer in solution… It was on the plaster surface, having some kind of affect.”
Obviously, she’s referring to the first 5 week test. But that quote is mixed in, where the previous paragraph is talking about the 6 and 4 month tests, making it sound like every time you get high stabilizer levels you end up with cyanuric acid falling out of solution. If that were the case, we really wouldn’t have to worry about high stabilizer, would we? Every time it hit 200, we’d just wait a few weeks for it to drop back to 100 and then vacuum the residue to waste.
3. Why in the world would they use freshly troweled plaster coupons to run this test? When would new, uncured plaster ever be exposed to cyanuric acid levels as high as 500 ppm? Not only is it not Real World, it’s not even Real Lab. After all, shouldn’t the lab make an effort to replicate the conditions you’re going to face in your customer’s backyards. Like I said, unless you bring a 50 lbs. bucket of cyanuric acid poolside and dissolve most of it in on Day One of startup, you’re never going to see the conditions they talk about in this report. And by the time you do, you’re going to have two or three year old, very well cured plaster. Of course, there will be folks who will want to play What If on this point. All I can say is that What If is a game for children and not one we ought to be playing in the laboratories and in the professional journals of our industry.
So, why do I care about the Arch Study? Because it is having an affect on our industries perception of cyanuric acid. Look at all the places I’ve found where it’s referenced as the report that shines the light on plaster damage caused by cyanuric acid:
That took five minutes of googling to come up with those links. And it doesn’t even scratch the surface of all the times this study is linked to in the forums - or the Finger Pulling Contest, as I like to call them - and probably 50 or 100 times throughout the thousands of forum threads discussing pools and plaster problems.
But now, whenever people google for the Arch Plaster Study, a link to this blog piece will come up as well.
What irritates me the most is how easily we were all duped. Honestly, why didn’t everyone say to themselves, “200 ppm stabilizer in the water may be high, but if I wait 5 weeks half of it is not going to fall out of solution, UNLESS I jack around with the water chemistry so much that EVERYTHING is going to fall out of solution.”
And that was the first chart on the page. We’ve all sat here and looked at that for all these years, and none of us, me included, has stopped to say, “Hey, wait a minute. That never happens.”
Is it just politeness that causes us to not ask those basic questions? I mean, when knowledgeable people have interviewed Dr. Meyer over the years, didn’t it come up? Something like, “Gosh, Dr. Meyer, you’re the first person in the history of history to report a 50 to 70% loss of cyanuric acid over a 5 week period. Are you sure you were watching that pH and not, intentionally or unintentionally, creating an environment where that was the only logical outcome?”
The Elephant in the Room, as it were.
Or is it because this report supports what a lot of people want to believe about cyanuric acid, and so it becomes the Straw Man for that camp? If you’re face is reddening as you read this, then maybe there’s some truth to that.
The craziest thing about all this is, I’ve heard there are people trying to DUPLICATE THE RESULTS OF THIS TEST and consider their tests failures when they don’t achieve the same results. You see, this thing has become the standard that other efforts are gauged by. It is now assumed that cyanuric acid damages plaster and it’s just a matter of holding your tongue right to achieve the same “proof” that Dr. Meyer achieved.
All I know is this thing gets referenced all the time, usually as “recent studies indicate that large quantities of cyanuric acid can even damage plaster”.
I’ve said it before and I’ll say it again: Lions and Tigers and Bears, oh my!
This study is being used by different groups of people to different ends. The folks at Arch are using it to generate heat for cya based products and a bump for sales of their calcium based chlorine and another reason for people to consider their alternative sanitizers, like Baquacil. People have argued with me that I’m wrong there because Arch also sells cya based products, too. Well, how is encouraging people to keep their cya level between 25 and 50 ppm anything but good for trichlor sales?
That tricity link is on the website of a company that’s big on UV sanitizing. There’s nothing wrong with that. UV sanitizing works and it’s not a scam to be selling the units. And throwing rocks at high cyanuric acid won’t hurt those sales, either.
This report supports a philosophy, a philosophy that high cyanuric acid is bad for us. And it is. The more I read and research, the more convinced I become that high levels of cyanuric acid are inhibiting our ability to effectively combat the growing threat of cryptosporidium outbreaks. Too, from what I've read, it does have the general effect, in high levels, of reducing the kill time of chlorine.
But it doesn’t destroy plaster. Not in the Real World. If a guy lets his pool get to 200 or 300 or 500 ppm cyanuric acid, he’s got enough other bad water chemistry habits to destroy the plaster without cyanuric acid having anything to do with it.
Now, I tried to play fair on this. I e-mailed Dr. Meyer on February 28th and asked her, “when you raised cyanuric acid to 250 and 500 ppm, did you use any correction factor on your observed TA?”
On March, 13th, she wrote back that, “yes, we did use a correction factor on our observed TA for the pool study that was run. We subtracted 1/3 of our CYA reading from the observed total alkalinity to get the carbonate alkalinity.”
I wrote again on March 14th to ask her about the issues of the cyanuric acid falling out of solution, and asked why they used new plaster vice cured plaster coupons for their tests.
She has not responded. If she does, and if she can explain any of this, then I’ll gladly amend what I’ve posted here.