If it was me, I'd call the people who installed the liner and see what they have to say about it. Also I'd check with my homeowners insurance. A friend of mine said his insurance would pay for a replacement liner when his wore out. That seems odd to me, but he swears that's what they said they'd do.

Also, it took a few years of low PH due to pucks before our liner finally turned white and wore out. I wouldn't think low PH would do it that fast??