Higher CYA levels

[PoolOwnerNumber9]

Continuing a discussion started in this thread. JasonLion

Richard, The book that comes with the Taylor test kit does mention some concern for toxicity. I think that it is probably equivalent to using Borates.

Since the cyanuric acid level decreases the effectiveness of the chlorine, shouldn't people limit their cyanuric to a certain maximum? I think that it should never get above 75 max.

 

[frustratedpoolmom]

Re: What's an Oxidizer do?

Gosh there are an awful lot of pools out there with CYA well over 100 ppm....if there is a toxicity level, that's a bit scary isn't it? Especially since pool stores will say in their printouts that levels up to 200ppm are "normal".....

 

[JasonLion]

Re: What's an Oxidizer do?

Richard, The book that comes with the Taylor test kit does mention some concern for toxicity. I think that it is probably equivalent to using Borates.

"Concern" is exactly the right word. Some people have expressed health concerns related to cyanuric acid. Some of these concerns have contributed to various states setting upper limits on the cyanuric acid levels allowed in public pools. The indirect effects of cyanuric acid also contributed to those rules being written, so it is difficult to say how significant the cyanuric acid health fears were.

However, none of these concerns have been supported by scientific evidence. There are no documented significant direct effect from cyanuric acid at anywhere near the levels used in swimming pools. However, cyanuric acid can cause well known indirect effects, lowering the effectiveness of chlorine below safe levels if the FC level is not raised to compensate.

 

[PoolOwnerNumber9]

Re: What's an Oxidizer do?

Note to frustratedpoolmom aka themodsquad: Anyone advising that cyanuric acid levels up to 200 are acceptable or even normal is giving bad advice. Maximum effectiveness is between 25 and 50 ppm. Anything over 50ppm provides little or no real new value. While there are no “Proven” toxicity problems, it does not make any sense to have high levels that provide no benefits and have the detriments of “possible” toxicity and definite reduction of chlorine’s effectiveness.

 

[duraleigh]

Re: What's an Oxidizer do?

#9,

Your maximum effectiveness for CYA seems a little low. Most of the SWG manufacturers recommend 60-80ppm. Over the years, I have seen benefit in moving my manually chlorinated pool to 60ppm.

I certainly think you're on the right track with reduced effectiveness at higher levels but the experiences on this forum seem to favor quite a bit higher ppm than you're suggesting. How did you arrive at the maximum effectiveness of 50ppm?

 

[PoolOwnerNumber9]

Re: What's an Oxidizer do?

Frustratedpoolmom:Also notice that the cyanuric acid shock chart, which you refer to, does not go above 100ppm. I wonder why? Notice how high the chlorine levels need to be with cyanuric acid that high? 40ppm just to shock! Provide some reference to anyone who advises that cyanuric acid levels up to 200ppm are “normal”.

Duraleigh: The book that comes with the Taylor test kit says “Above 50 ppm, only marginal stabilization benefit is observed”. Document here http://www.taylortechnologies.com/Chemi ... ntentID=36 and here http://www.taylortechnologies.com/learn ... mistry.asp

 

[frustratedpoolmom]

Re: What's an Oxidizer do?

Note to frustratedpoolmom aka themodsquad: Anyone advising that cyanuric acid levels up to 200 are acceptable or even normal is giving bad advice. Maximum effectiveness is between 25 and 50 ppm. Anything over 50ppm provides little or no real new value. While there are no “Proven” toxicity problems, it does not make any sense to have high levels that provide no benefits and have the detriments of “possible” toxicity and definite reduction of chlorine’s effectiveness.

Please be rest assured that after everything I have learned I would NEVER recommend that or assert it is "Normal". My remark was sarcastic... My reference was to a Pool Store Print out of test results that said the "acceptable range was between 30-200".

Having lived thru the CYA catastrophe and found TFP because of it, I think my understanding of CYA is pretty good all things considered. What is scary to me is that there are ALOT of pools out there with extraordinary high levels and the people are clueless, thanks to pool stores that don't educate; nor do they want to educate their employees on the pros or especially the cons of CYA levels.

 

[chem geek]

Re: What's an Oxidizer do?

PoolOwnerNumber9,

Look at the post by mas985 later on in this thread to see the experiment that he did that showed that higher CYA levels do protect chlorine breakdown from sunlight in a non-linear way such that even proportionately higher FC levels are still protected (i.e. you lose less absolute FC at higher CYA levels in the 60-80 ppm range). This was an unexpected result and my current guess about it involves the non-linear absorption of UV by CYA with depth combined with imperfect mixing near the surface (this post goes into some details). The Taylor book is wrong as is PPOA and several other sources. We've had too many cases (in addition to Mark's experiment) of non-linear beneficial effects of lower chlorine drops at higher CYA levels (even at the same FC/CYA ratio) for this not to be true. This would not be the first time that industry "wisdom" was not true.

As for toxicity studies with CYA, the most comprehensive summary is shown here for Cyanuric Chloride which in water hydrolyses to Cyanuric Acid. The oral LD50 (lethal dose for 50% of people) is about 320 mg/kg of body weight while the dermal LD50 is > 2000 mg/kg. The LOAEL (Lowest Observed Adverse Affect Level) is 50 mg/kg. These are huge amounts compared to what one is exposed to in a pool where 100 ppm CYA is 100 mg in a liter of pool water (which you don't normally drink and you are normally far more than 1 kg or 2.2 pounds in weight). There is also this EPA link in section 13.1b that shows oral LD50 > 5000 mg/kg. Section 13.3c shows similar results for dermal LD50. You can read the other data as well. Boron (shown here) is more toxic in terms of oral dose at pool water levels which is why we recommend that dogs not regularly drink pool water with Borates in it (note that 50 ppm is measured as Boron so is equivalent to 286 ppm Boric Acid).

The bottom line is that CYA at pool levels is VERY far from toxic effects and you'd have to drink lots and lots of pool water at very low body weight before even getting to first symptoms of any kind. So having a limit of 100 ppm is reasonable given children or babies that might gulp water, but it's a rather safe limit. Mostly, as you say, very high CYA levels have other more serious side effects of reducing chlorine effectiveness, but it's roughly proportional to the FC/CYA ratio and not a rapid dropoff (except from no CYA to a small amount of CYA). This post goes into details about how the FC/CYA ratio comes from the equilibrium chemistry.

Richard

 

[frustratedpoolmom]

Re: What's an Oxidizer do?

Hey Richard, they are talking about you...word is getting out that you really know your stuff! (We already knew that.... :bowdown:

http://ths.gardenweb.com/forums/load/po ... 15039.html

 

[PoolOwnerNumber9]

Re: What's an Oxidizer do?

Richard, at a cyanuric acid of 80, you recommend a free chlorine of 9ppm and a shock level of 30ppm. However, due to the effect of the stabilizer reducing the reactivity of the chlorine, any test –(reagent or electronic)- will read artificially low. So, your real levels are closer to 12 and 40. Of course a cyanuric of 80 will hold the chlorine longer, but you’re getting awfully close to totally locking the chlorine up. I think that these levels are too high. I don’t like to keep the chlorine any higher than a maximum of 5 – 7 due to the negative effect on heaters and such. Like I said, I set a limit of 75ppm as a maximum for cyanuric acid. In this post the poster mentioned a cyanuric of 100 and you did not recommend any remedial action. As such, can I assume that you are OK with such a high level?

 

[Guest]

Re: What's an Oxidizer do?

Note to frustratedpoolmom aka themodsquad: Anyone advising that cyanuric acid levels up to 200 are acceptable or even normal is giving bad advice.

Actually, Chemtura's corperate stand is that CYA levels up to 200 ppm are acceptable for residential pools. I persinally disagree. If you don't know who Chemtura is then you might know some of their brands--Bioguard, Guardex, Sun, PoolTime, Omni, and Aquachem to name a few of them! Chemtura happens to also be one of the largest manufacturers of triclor.

 

[PoolOwnerNumber9]

Re: What's an Oxidizer do?

Richard, at your chart here
pool-water-chemistry-t628.html
you show that the half life of free chlorine at 50ppm CYA is nearly the same as it is at 100 ppm. You say “A Little CYA Goes A Long Way” and “The following is a graph showing that a large amount of the benefit of CYA protection of chlorine from UV (sunlight) is already there at around 20 ppm”. Your chart shows a logarithmically diminishing protection ending at 100ppm. It appears that your chart shows exponentially diminishing returns after 50ppm.

 

[Guest]

Re: What's an Oxidizer do?

Frustratedpoolmom:Also notice that the cyanuric acid shock chart, which you refer to, does not go above 100ppm. I wonder why?
Basically because it's impossible to accurately test CYA with standard turbidity tests above 100 ppm!

Duraleigh: The book that comes with the Taylor test kit says “Above 50 ppm, only marginal stabilization benefit is observed”. Document here http://www.taylortechnologies.com/Chemi ... ntentID=36 and here http://www.taylortechnologies.com/learn ... mistry.asp

The Taylor book is good but does contain some misinformation such as the formula for breakpoint chlorination that , while widely accepted in the industry, is inaccurate and the info on TDS which would mean, accoriding to the Taylor book that EVERY pool with a SWG would have a TDS that is too high. It is not the TDS that is important but the different ionic species present. If they are mostly sodium and chloride ions then they are benign but if they consist of high levels of cyanurates, sulfates, or metalic cations (such as calcium or copper) then they are problematic.

 

[JasonLion]

Re: What's an Oxidizer do?

Note to frustratedpoolmom aka themodsquad: Anyone advising that cyanuric acid levels up to 200 are acceptable or even normal is giving bad advice.

No one around here is recommending anything above 80. But when pool owners come to us with higher levels and they have strong reasons for not lowering their CYA levels we will explain to them how they can manage their pools with high CYA levels.

The book that comes with the Taylor test kit says “Above 50 ppm, only marginal stabilization benefit is observed”.

Yes, a number of sources do say that. That doesn't make it true however. There are many many things that are "common knowledge" in the pool industry that aren't true. In this particular case, there was an interesting study that reached the conclusion that levels above 50 aren't useful. Since then, quite a number of people have documented significantly reduced chlorine usage at higher CYA levels, while no one has been able to duplicate the results reported in that study.

 

[PoolOwnerNumber9]

Waterbear, here is Richard's chart
pool-water-chemistry-t628.html
here he shows that the half life of free chlorine at 50ppm CYA is nearly the same as it is at 100 ppm. He says “A Little CYA Goes A Long Way” and “The following is a graph showing that a large amount of the benefit of CYA protection of chlorine from UV (sunlight) is already there at around 20 ppm”. His chart shows a logarithmically diminishing protection ending at 100ppm. It appears that his chart shows exponentially diminishing returns after 50ppm. What reference can you show to support this: "Chemtura's corperate stand is that CYA levels up to 200 ppm are acceptable for residential pools"?

 

[PoolOwnerNumber9]

For anyone who wants to respond: What is the highest level of cyanuric acid that you are willing to accept? What's your limit?

 

[frustratedpoolmom]

Re: What's an Oxidizer do?

Gosh there are an awful lot of pools out there with CYA well over 100 ppm....if there is a toxicity level, that's a bit scary isn't it? Especially since pool stores will say in their printouts that levels up to 200ppm are "normal".....

I just want to clarify so that there is no misunderstanding here that my sarcastic emoticon was referencing the Pool Store advice that levels up to 200 are normal or acceptable, which they are not and I do not agree with that at all. I was not in any way directing my ever-so-present sarcasm at a new poster, PO#9, and I was in agreement with him that the CYA needed to be lowered. I was most certainly not making a recommendation that it was normal. Many of the regular posters on here recognize my aversion to high CYA levels, as well as my aversion to pool stores in general...note my signature, which has read almost exactly that way since I first found TFP....

Hope this clears things up. (little pun there....)

 

[JasonLion]

What is the highest level of cyanuric acid that you are willing to accept? What's your limit?

In my personal pool I would never intentionally raise CYA above 80, but would allow a level of 90 for some period of time if there was some reason not to lower it right away.

These days, I would swim in a pool up to about 150, or possibly even 200, if I knew that appropriate FC levels were being maintained. At the same time I would counsel the owner of that pool to lower their CYA level to something under 100.

When I bought my current house, the CYA level was over 300, as far as I could tell, and the water was clear and sparkling. I spent a month and over $300 on replacement water getting the CYA level down. Not everyone is willing to spend that much or wait that long. PoolOwnerNumber9, what would you do in that situation?

 

[frustratedpoolmom]

For anyone who wants to respond: What is the highest level of cyanuric acid that you are willing to accept? What's your limit?

I accepted 70 for all of last summer....Long Story . This Spring I opened and lowered it to 40, it's now at about 35 or so.

I just swam in a slightly cloudy public pool last Friday, who knows what their numbers were. I'm going to one tomorrow. Perhaps I should bring my test kit with me and ask them if I can test the water before I pay admission....

When I advise people I give them the recommended levels in Pool School. Many people are so overwhelmed by the time the find us that they balk at draining their pool, they balk at purchasing a good test kit, they just want an easy fix. They don't want to understand they whys or the hows, they just want their pool clear as quickly as possible, apparently regardless of the money wasted on pool store chems. But suggest draining and we get "the cost of water, etc" but suggest a good test kit "but I've already spent soo much money as it is"... the reasons are endless.

We're just trying to give them the best advice possible and offer what little assistance and encouragement we can. I for one would have torn out my pool last year were it not for the members of this forum, especially Sean, Jason, Waterbear, Mermaid Queen and Richard.

Let us never forget the sound advice of the pool store May, 2007 when I asked why they didn't test my CYA: "You don't need to worry about that."....

 

[PoolOwnerNumber9]

JasonLion, it is my understanding that a cyanuric acid level over 100 would totally lock up all available chlorine and make it ineffective. Is my information incorrect?