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