Calcium Hardness (CH) for Vinyl Pool Liners

[chem geek]

There is this discussion over at Trouble Free Pool that has uncovered the apparent fact that granulated calcium carbonate is the common filler in vinyl pool liners. I thought I'd bring that discussion over here as well.

I think that in practice it's not an issue given no problems actually seen with many pool owners having low CH water and vinyl pools, but I had always assumed there was no calcium carbonate in such vinyl liners and that apparently is not the case. The questions are whether it actually dissolves in low CH water vs. being bound more tightly in the vinyl matrix and whether even having it dissolved matters.

[CarlD]

Going into my 9th season with my liner without ever worrying about calcium in the water levels. When I test it, it's always low. You'd think after 9 years a problem with low calcium would have cropped up. It hasn't.
That's one data point.

[madwil]

CH in a chemical formula is Carbon and Hydrogen- Ca is Calcium- the guys at TPF are mixing apples and oranges!
CH is Calcium Hardness in water testing, not a chemical formula...
But I guess they figured that out themselves- lol!

[chem geek]

No one at TFP was mixing anything up. It was a guy at a pool store who got it wrong and the poster at TFP knew that, tried to explain to the pool store person what a hydrocarbon was (i.e. CH is carbon with hydrogen attached) and started the thread as an example of the mis-information at some pool stores. The thread title was facetious.

Thanks Carl. That's really what I'm looking for -- real-world examples of older liners in pools with low CH with no problems and not seeing any examples of ones with problems, at least not in any higher proportion than in water with higher CH. Also, I wanted to let people know here that indeed there may be some calcium carbonate in vinyl liners so that no one says that there isn't. We can still give appropriate advice and say that lower CH isn't a problem, but we shouldn't say that vinyl liners don't have any calcium carbonate whatsoever. It would be nice to know chemically why it may not matter, but real-world positive results will do.

[CarlD]

Hi Richard,
I don't track TFP's stuff at all so I wouldn't know. I think the other mods have a similar experience to mine, and I know Al and Lisa have vinyl liners. I'm 99% sure Jan does too, and we all never bother with calcium levels. Al's liner has got to be close to 15 years old, too.

You'll need about 15 data points before you can legitimately determine a statistical trend--too much noise below that.

Meanwhile, don't you have a scrap of liner around you can grind up and test for calcium carbonate? Give me a couple of more years and I may be able to give you mine!

Carl

[aylad]

My liner was 9 years old when I had to replace it, and the original rips that caused the need for replacement were well above the waterline, not below....

The calcium in our fill water is less than 20 ppm and I think I might have used cal-hypo for chlorination 4 times in that 9 years, in a pinch when I was out of bleach. So you can add that one to the count...

Janet

[PoolDoc]

Hi Richard, All;

Richard, if you can dig to the bottom of this, it would be very helpful to many. I did some work on it years ago, but ran into problems and gave it up. A lot of my info came from a product engineer at Canadian General (http://www.cgtower.com/). At that time (15 years ago), they were making a big part of the PVC sheeting used by US liner mfgs.

What I learned from him was the following:
+ calcium carbonate is used as filler in some, but not all (he thought) sheet.
+ low calcium was not (he thought, supported by some casual testing) going to cause premature failure.
+ like other flexible PVCs, vinyl sheet is a mixture of PVC, plasticizers, UV stabilizers, colorant, filler, and ??
+ there is no standard formulation.
+ liner color may, or may not, be in the sheet.
+ liner patterns are printed on by the liner mfg.
+ at that time (as I recall) he thought that NONE of the liner mfgs were sheet mfgs.
+ there were 2 or 3 mfgs of sheet.
+ sheet formulation was proprietary and varied from company to company, but also from time to time.
+ the same model & weight of liner might be actually made from 3 or 4 different instances of sheeting, each with different composition and properties.
+ many of the liner mfg did not understand the intricacies of PVC mfg, and thus did not understand what they were buying. There particular concerns often focused on manufacturing properties, like print-ability and suitability for their equipment.
+ printing ink varies too, and there's no guarantee that the ink for a particular model is the same over time.
+ generally, low pH tended cause plasticizer leach-out, but he didn't have data tying time and pH to damage.

Bottom line for me: there was no way to tell from one liner to another, or even from one liner today to the same liner tomorrow, and thus there was no valid way to get very specific about what would affect which liner in what way. Even with the minimal exposure to liner pools I've had, I've seen big differences in liner life expectancy in similarly managed pools.

Ben

[PoolDoc]

Whoop! Whoop! Whoop!

CGT is now making finished sheeting and has a BUNCH of tech data:
http://www.cgtpoolliners.com/cgt-technical-manual.htm

I'll archive copies, but don't have time to read it all now.

Ben

The content in this one will be particularly of interest:
http://www.cgtpoolliners.com/cgt-tec...bulletin-4.htm

(I lied; I've ended up reading quite a bit as I archived. A lot of the data dates to 2007)

[PoolDoc]

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

[giroup01]

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