(ChemGeek) Re: Did you know that Vinyl liners contain calcium?
James,
The manufacturers quoting the same standard water balance parameters isn't so relevant since some of these same guys also claimed that bleach shouldn't be used (though some to say chlorinating liquid is OK) so their credibility is a bit suspect. However, as far as an additive/filler, it's clear from your references that granulated calcium carbonate is often used. So the question is whether water that is not saturated with calcium carbonate attacks it or whether it is sufficiently embedded into the vinyl for there not to be a problem as compared to plaster pools that clearly have large areas of calcium carbonate directly exposed to the water.
I wonder if there some sort of experiment that could be done, perhaps at hot water temperature to accelerate the process, with vinyl samples exposed to buffered water with virtually no CH vs. water saturated with calcium carbonate, both at a pH of around 7.5. We might then see if there is any difference in elasticity, coloration, folds, or other effects. We could also see if the CH and pH rise in the no-CH water vs. the saturated water which would imply leeching and dissolving of calcium carbonate from the vinyl. We've never had any reports of people seeing unusual pH or CH rises in vinyl pools, but then again most aren't checking their CH levels.
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So as long as the amount of calcium carbonate in vinyl is low (< 7%), it seems that even acidic conditions don't cause serious problems. The implication here is that low CH levels may not be an issue with these low levels of calcium carbonate.
We may never know for sure about this issue, but at least we've got more info to ponder..