I have a brownish yellow stain around the perimeter of my pool.
40,000 gallon
vinyl liner - L shape
about 6 years old

There was a faint stain the end of last season- I tried letting the chlorine level drop and added stain remover at end of season- it disappeared
Same stain early this seaon- tried the same thing and the stain went away
Now a few weeks later it is back and worse then ever.

I am not sure if it is metals - in reading the posts I think it may be and I need to try to suspend it??

I was told at the pool store(I know that is a no no so that is why I am asking here) That it is metal because this season about 2 days after using stain remover my water showed high for copper. They said that it takes a week for it to work its way out of the water?
Then when the stain reappeared- it showed no metals at all when tested- They said the metals were no longer showing in the test because they were not in my water- but back in my liner

Is this so?

I have always kept my alkalinity- PH and chlorine in correct ranges
Last year I found this site and switched to chorline- especially for shocking because it does not cloud - so nice

This is driving me crazy- and I find it hard to keep my chlorine level high- it keeps dropping but CYA is good.

Any ideas on who to listen to- what to read- or what else to test?

Thank you for any help that you can give me.