High Chlorine and Vinyl Liner

[el_steak]

Will high chlorine (+40ppm) over a long period (5+ days) damage or discolor vinyl liners?

I've read that affirmation in quite a few posts recently but I also vaguely remember seeing a test done by somebody on this forum where pieces of vinyl liner were left soaking in bleach for several days with no visible effect. I searched the board but couldn't find the post.

My pool is only 2 years old, so the liner is in perfect condition. However, I've seen a few older pools with discolored vinyl liners, but the discoloration was above the water line instead of under it. That led me to think it might be more due to the sun / UV rays than high chlorine.

 

[frustratedpoolmom]

It depends on how high the CYA level is. If the water was low in CYA that high a FC level could be damaging.

Damage to liners is often caused by improperly added chemicals, poor chemistry, etc. and it's easy to point to chlorine as the culprit, when that's not always the case.

For example, running with low ph for long periods can be very damaging. Allowing cal-hypo or dichlor to sit undissolved can bleach out the vinyl...

 

[JasonLion]

Low PH is far more likely to damage a vinyl liner than chlorine is, though chlorine can cause problems if it gets high enough for long enough and CYA isn't very high.