Bleach & Vinyl Liner

[chem geek]

The higher CYA level slows down the chlorine loss from sunlight in two ways, but one of those ways is in shielding lower depths from the UV rays of the sun (the CYA directly absorbs UV rays). This is a non-linear effect such that higher CYA levels significantly reduce the amount of UV that reaches lower depths. So it is quite possible that Janet's higher CYA level protects her vinyl pool bottom from fading while your lower level doesn't, even with less time in the sun.

I also seem to recall that Janet's pool is deep with a maximum depth of 8 feet. Even at the same CYA level, that would also make a difference.

This would imply that a higher CYA level would be a way to have vinyl liners fade more slowly, at least at lower depths, but that requires diligence since you have to maintain a higher FC level and it's harder to fight an algae bloom at higher CYA levels.

This is all nice theory, but we don't have enough cases to know if this is truly what is going on.

Richard