Safe pH levels for vinyl pools

[SalemCastles]

It was wrong on so many levels that I just couldn't respond nicely.

[Watermom]

-- not sure what you meant but ................ maybe you meant what I was thinking. Adding a bunch of pool store goop to perfectly clear water often produces results such as these that Barry is now facing. Lesson most likely learned. Now, to get it back to perfectly clear!

[SalemCastles]

Yes that's what I was thinking ... if it ain't broken don't try to fix it.

[SalemCastles]

I'm sorry I have upset you however your post was such that it frustrated me. You must know why you are pouring this stuff in your pool BEFORE doing so or ask first as there are many here to help you. What are your numbers? What are the ingredients that you're using? As mentioned the only thing you need to prevent issues is chlorine, maintained at the correct levels and SUPPORTED by the correct balance and you will enjoy crystal clear great feeling water. The most important supporting factor being PH. Again I'm sorry for your trouble.

[SalemCastles]

If it was my pool I'd get your Dad to put in 20 - 25 oz of Cal Hypo every 2nd day ... raising your Chlorine by 4-5ppm. If he's going to test it then he can adjust as necessary but I would want to stay closer to 5ppm or more than on the lower side until you get some stabilization going for you.

[SalemCastles]

Since you haven't been measuring your numbers up until now it's possible your PH has been low for a fairly long time. It's true that a high acid level can damage your pool especially if you have metal components such as as a heater inline or low quality stainless steel ladder etc. but for practical reasons I wouldn't sweat it that much. If you can get the PH up a bit before you leave then all the better otherwise just go and have a great vacation and deal with it when you get back.

[SalemCastles]

pH Effects

The joint study investigated the effect on vinyl of water pH between 2.0 and 10.0. A total of 224 white, blue and black vinyl samples were exposed to the ambient temperature and water at various pH levels between 2.0 and 10.0 for an extended period of time. During the test period, the total alkalinity in the test water was maintained at 150 parts per million, calcium hardness was at 100 ppm and the starting cyanuric acid concentration was 100 ppm.

Tests were conducted with the free available chlorine maintained at either 1.5 ppm or 20.0 ppm (The low value was used because it reflects common sanitizer usage levels; the high value was chosen because intermediate levels had limited effects on the vinyl. Throughout all investigations, pH was observed as the more significant variable.)

The effects upon the vinyl of water pH in the 2.0 to 10.0 range were determined with the free chlorine maintained at 1.5 ppm. The results were as follows:

Exposed samples where pH was maintained in the 7.0 to 7.5 range exhibited no adverse effects on the vinyl.
The lower the water pH drops below 7.0, the greater the incidence of wrinkling, loss of tensile strength, elongation and fading. Low pH (the acidic range) was found to have a more adverse effect than high pH (the alkaline range).
As the pH increases above 7.6, the vinyl loses weight and expands.
The lower the water pH drops below 7.0, the greater the vinyl’s weight increase.


It is important to note that the vinyl material remained functional throughout the tests.

[SalemCastles]

Aylad ..you were in this thread..seems like it's just one big circle and stuff gets dropped and added to support whichever point of view. http://www.poolforum.com/pf2/showthread.php?10939-Calcium-Hardness-(CH)-for-Vinyl-Pool-Liners


Anyhow:

+ OK pH range is 5 - 9
+ The idea of adding calcium carbonate scared him, because he said high pH is more damaging than low pH.
+ There are definitely variations in liner material quality, and there is imported knock-off material. But he thought the patterns (see website) are likely to indicate source fairly well.

Richard, you might want to talk to 'Flee-ler'.

Ben

Furthermore there seems to be some other theory's ... http://www.cgtpoolliners.com/cgt-technical-manual-2008/cgt-technical-bulletin-10.htm


Research by both chemical suppliers and vinyl manufacturers have confirmed that wrinkles in swimming pool liners develop because of the growth of the liner's dimensions due to an excess of absorbed water. Technical articles published in the past have stressed the adverse affect of low pH as the main cause of liner growth. However, recent experiments have shown that high levels of sanitizers, whether bromine or chlorine are the primary cause behind excessive water absorption. If the sanitizer level is allowed to remain high, double triple or even four or five times the normal amount of water can be absorbed. Therefore, controlling sanitzer levels is the number one priority when maintaining proper water chemistry, which is essential, if wrinkling problems are to be avoided.

pH and cyanuric acid stabilizer levels are important secondary factors because they control the activity of the sanitizer.

I really care more about what is right then who is right ... balanced informed decisions are for each pool owner to make. Ruining a guys vacation because he's scared to death he might get a wrinkle in his pool liner doesn't seem too balanced to me.

[waterbear]

I really care more about what is right then who is right ... balanced informed decisions are for each pool owner to make. Ruining a guys vacation because he's scared to death he might get a wrinkle in his pool liner doesn't seem too balanced to me.

The point you seem to be missing is the point I made before. WHAT is causing the pH to drop and the TA to be depleted? Since we don't know the answer to that is it much safe to get the pH up BEFORE he leaves since we don't know how quickly the pH will drop. That is what is right!

[Watermom]

Ruining a guys vacation because he's scared to death he might get a wrinkle in his pool liner doesn't seem too balanced to me.

I don't think we ruined a guy's vacation. He came and asked for advice and that is what we gave him.

[SalemCastles]

The point you seem to be missing is the point I made before. WHAT is causing the pH to drop and the TA to be depleted? Since we don't know the answer to that is it much safe to get the pH up BEFORE he leaves since we don't know how quickly the pH will drop. That is what is right!

Perhaps I am but that's mainly due to the fact that we have no indication that anything is driving the PH down. It might very well have been at the level for the last 4 years. We don't know because it wasn't being tested. Couple that with the notion that high CL is more damaging then Low PH I just think it should be mentioned in passing in case it's true.

[waterbear]

Perhaps I am but that's mainly due to the fact that we have no indication that anything is driving the PH down. It might very well have been at the level for the last 4 years. We don't know because it wasn't being tested. Couple that with the notion that high CL is more damaging then Low PH I just think it should be mentioned in passing in case it's true.

Then based on what you say we should never shock a liner pool because high sanitizer will damage the liner and cause it to wrinkle by taking on water... empirical evidence notwithstanding.
(And this discussion is more suited to the china shop than in this hijack of the OP's thread.)

[aylad]

DurhamHouses, our advice to the OP is not changing....whether you agree with it or not is up to you. At this point, if you want to continue the debate, please do so in the China Shop so that the original poster can continue his thread here if he chooses.

Janet

[CarlD]

It was wrong on so many levels that I just couldn't respond nicely.

Then don't. We'll take care of it.

Carl

[CarlD]

Since many of us have run high levels of sanitizer for many years in liners that are 9, 10, even 15 years old, it's a little hard to tell which wrinkles are due to excessive chlorine, and which are due to age, sun, temp changes, shifting, etc.

DurhamHouses, you need to understand that many users come here BECAUSE they have problems they cannot solve and the pool store has only made worse. We have helped thousands here over the last 10-15 years and somehow managed to get their pools cleaned up and running nicely all on our own. Our advice is always intended to be clear, easy to follow, and, most important, effective. We also WELCOME new users and have answered the same elementary questions hundreds of times. That's what we are about. If you cannot accept that, this isn't the forum for you.

You are welcome to debate alternative treatments and techniques in the China Shop but not while we are working to help an OP clean up their pool. It is merely disruptive and confusing.

[PoolDoc]

The joint study investigated the effect on vinyl of water pH between 2.0 and 10.0.

To make claims like this, Durham, you'll need to provide a link to the study you're citing.

[giroup01]

Probably "Chemicals and Vinyl" by Don Ridpath, Pool & Spa marketing, 1998.

But this thread is all chopped up - where's the beginning?

[PoolDoc]

It began where it shouldn't have, in the middle of a poster's questions about how to get his pool ready for vacation.

Is that article available online? If not, do you have a copy you can email me (poolforum AT gmail DOT com)? Who is Don Redpath?

Ben

[giroup01]

http://piscines-apollo.com/docs/chemicals_and_vinyl.pdf

Basically if the liner is discolored it means too much chlorine, if it's wrinkled it means pH too low. pH is what kills liners. The calcium content is dissolved and the liner swells up and wrinkles. Water with high chlorine concentration can then penetrate further into the liner. The liner loses its elasticity, it elongates etc, we've all seen it.

[PoolDoc]

Actually, according to two different engineers -- 10+ years apart -- at Canadian General, the calcium content is mostly irrelevant. But, the swelling at low pH is consistent from all sources.

However, what you are saying about chlorine penetrating is also contradicted by all vinyl engineers I've spoken with -- the consensus I've encountered is that chlorine at pool levels (<100ppm) doesn't affect the vinyl sheeting, but CAN damage the printed patterns, and some dyes, especially medium blue.

Also, the article refers to a study, but doesn't cite it or state when and where it took place nor who conducted it. Nor is there any bio or CV info on "Donald Redpath". The article reads much like one of the "expert" articles from Service Industry News . . . and those aren't entirely trustworthy.

So, unless there's better info, I'm going to stick with the info Chem_Geek and I have been given by vinyl sheet mfg engineers.

Ben

[giroup01]

I'm saying that once the vinyl swells up, it becomes more porous and can absorb chlorine more deeply into the layers.
But it doesn't matter really. The Europeans have really researched this, my info is from AFNOR documents and internal documents from the manufacturers over there. There may exist some differences in the manufacturing between the continents.

[SalemCastles]

So the real context of the discussion is are you being alarmists? I think most definitely you are. So I believe Carl is right when he suggests this forum is not for me. I quoted below to illustrate according to Ben just a few months ago that the engineer said a of PH 5-9 is ok. But what does the manufacturer know. The study went from a PH of 2-10 and said that it gets progressively more likely below 7 however other factors contribute ... these other factors such as high cl with no or low CYA are routinely recommended here with no qualification. At the end of the day it's just a swimming pool. In all cases the function of the liner was never compromised ... saying you have to do this or that right now or you WILL damage this or that is just (with due respect) a way to raise your self importance. I do have a last question ..how do I delete my account?

http://www.poolforum.com/pf2/showthread.php?10939-Calcium-Hardness-(CH)-for-Vinyl-Pool-Liners


Ok, I got side-tracked, and called CGT. I'm ADD and eternally curious; whaddya expect?

Spoke to a liner product engineer, "Immanual + foreign last name" -- it bugged him that I couldn't understand his name, I so I gave up. After we spoke for awhile, he transferred me to "Carl Flieler" (sp?) => Carl Flee-ler who is the pool liner guy, but he wasn't in.

Anyhow:

+ OK pH range is 5 - 9
+ The idea of adding calcium carbonate scared him, because he said high pH is more damaging than low pH.
+ There are definitely variations in liner material quality, and there is imported knock-off material. But he thought the patterns (see website) are likely to indicate source fairly well.

Richard, you might want to talk to 'Flee-ler'.

Ben

[CarlD]

I do have a last question ..how do I delete my account?

I'm sure Ben will be able to accomodate you.

We have acceptable ways of challenging our pre-conceived and previously demonstrated premises, and unacceptable ways. It is as simple as that.
Several have been challenged, and challenged successfully. But how you challenge is what matters.

Good luck to you.


Carl

[giroup01]

DurhamHouses,

Keep in mind that these are pool forums aimed at residential pool owners, little self-help communities. There is a definite "dynamic" that exists within these forums. I think it was PoolDoc, in an earlier version of this board, that said "As I rule I'm right and you're wrong." The underlying aspect, the common ground in all of them is that the participants don't know what they don't know. From that starting point discussions can go anywhere.

At the end of the day it's just a forum.

I can have a graph by one of the manufacturers that shows the absorption of water by a liner as a function of pH over time:

http://piscines-apollo.com/images/water_absorbed_liner.jpg

But then you'll have somebody come along and question it, or say it ain't valid for whatever reason, without any background knowledge or knowing the context.

Then a decision is made, like what just happened, to favor another bit of information, or another source, hence the information is never complete, and that decision forms the basis for what now becomes the accepted answer, the "truth".

Like I said, it doesn't matter, really. It's the nature of forums. Just let it go.

[PoolDoc]

Durham, you are overlooking a key point: when people test pH 6.8 or 7.0, that does NOT (depending on their testor) mean that the pH is 6.8 or 7.0. Rather it means that their pH is 6.8 (or &.0) OR BELOW.

The reason is, their testors only go to 6.8 or 7.0, so they read any result that is that yellow OR yellower as the low value on their kit.

You made two mistakes.

Your first was to overlook the fact that the pool had not been 7.2 and then drifted down to 7.0. Rather it had been largely untested, which means that none of the moderators really knew what the pH was: for all they knew, it WAS 5.0, because that pH level would have produced the SAME reading -- for many pool owners, using many of the standard kits -- as if it was actually 6.8 or 7.0.

Now, I'm not sure that everyone who posted understood WHY it is important to get the pH above 7.2, or that an ACTUAL pH of 6.8 is not damaging to liners. But, the bottom line is, whether they understood or not, THEIR advice was operationally correct and yours was wrong . . . because neither you nor they could be sure the the OP's pH was NOT 5.0, until they raised the pH to the mid-range of their tester!

Your second mistake was in challenging the moderators in the middle of a post, rather than here.

The advice given here is not perfect. I'm aware of many flaws in some of the posts, including some of mine. But the fact is, the advice given here is, all things considered, probably the best advice a residential pool owner can obtain on operating their pool effectively and economically.

But . . . it only works, when people follow it. And when someone challenges the moderators mid-stream, what users tend to do, is not wade through all the complexity of the various points in the argument, but rather they retreat to a what is familiar and thus psychologically more comfortable: pool store advice.

So, not only was your advice wrong in its substance (if not in all the reasoning behind it) but also your challenge in the form you presented it likely to result in the OP bailing out and proceeding to follow even WORSE advice.

I'm not sure whether you belong here or not.

Once you transition from asking questions, to posting answers, our expectations of your behavior go up considerably. We have an area for public debate, that's been heavily used over the years. But that place is NOT in the middle of threads from someone about to go on vacation.

So, if you feel yourself unable to offer my moderators the respect they've earned from 10 years of trying to help 1000's of people, by bringing your challenges to the right section and posing them with a polite and careful manner . . . then I agree, the PoolForum is not for you. There is no shortage of forums where rudeness and disorder are the norm.

Sincerely,

Ben Powell

[chem geek]

The study went from a PH of 2-10 and said that it gets progressively more likely below 7 however other factors contribute ... these other factors such as high cl with no or low CYA are routinely recommended here with no qualification.
We don't recommend no or low CYA with high FC (chlorine) here so I don't understand this statement. The active chlorine (hypochlorous acid) level recommended here (see Best Guess Chlorine Chart (http://www.poolsolutions.com/gd/best-guess-swimming-pool-chlorine-chart.html)) for normal chlorination (FC that is 7.5% to 15% of the CYA level) is the same as found in a pool with 0.07 to 0.14 ppm FC with no CYA while the level for shocking (roughly an FC that is 40% of the CYA level) is the same as found in a pool with 0.6 ppm FC with no CYA. This is based on known equilibrium chemistry described in this paper (http://richardfalk.home.comcast.net/~richardfalk/pool/OBrien.htm), and computed in this spreadsheet (http://richardfalk.home.comcast.net/~richardfalk/pool/PoolEquations.xls), and validated by pathogen kill times, oxidation rates and ORP as described in the "Chlorine/CYA Relationship" section of this post (http://www.troublefreepool.com/certified-pool-operator-cpo-training-what-is-not-taught-t18432.html) and also validated by the tens of thousands of pools on this and other forums that have algae growth prevented by following the chlorine/CYA relationship.

Also note this info (http://www.geomembrane.com/TechPapers/5Questions.htm):


Then we have fillers. Calcium carbonate is often used as a filler in plastics. Depending on the amount used in a blend, calcium carbonate can increase the modulus, increase the hardness and at very high loadings decrease the cost of the formulation. It was found that at levels less than 7% by weight the physical properties were not significantly affected and that, at levels over 20%, the physical properties were compromised and the chemical resistance severely compromised.

Stanford et al. (1979) showed that high filler loadings resulted in excessive weight gain and, thus, poor chemical resistance. A PVC formulation incorporating high calcium carbonate amount is by far the most significant negative factor in acidic leachate environments. When exposed to acidic leachates, and with 37% HCl, formulations with less than 7% calcium carbonate, incorporating a branched or linear phthalate, had less than 5% weight change and – more importantly – were still very flexible.
:
Calcium carbonate filler loadings of greater than 7% should be avoided in low pH (acidic) environments.
It would be good to know if all vinyl pool liner manufacturers used less than 7% calcium carbonate in their formulations. Maybe some don't and has led to the idea that low pH can be harmful to even the integrity of vinyl pool liners.

[waterbear]

Then don't. We'll take care of it.

Carl
I am sure he will find a happy home at TFP.

[PoolDoc]

I am sure he will find a happy home at TFP.

There's nothing like giving your competitor your mostest favoritest customers! :rolleyes:

[CarlD]

There's nothing like giving your competitor your mostest favoritest customers! :rolleyes:

"Martin! Your customer!" -- Hugh Grant, "Notting Hill"