Weird staining on exactly 2/3 of pool

[xray328]

I’m going to do the absorbing acid daal but any idea what would cause this? As in why does it follow the seam line like that?

 

[Texas Splash]

That is odd. How old is that liner? Have you tested the discolored area with Vitamin C tablets yet? That will tell you if it's iron and worth the AA treatment. I'm wondering if it has something to do with how the liner was fabricated and perhaps a recent chemical change.

By the way, can you post a set of water test results?

 

[markayash]

That is weird, did you test it and make sure it's iron? Mine always comes back to the same place but not as defined

 

[xray328]

Iron confirmed. I don’t have current numbers as we just opened it last week but I’ve been following TFP since day one. Liners about 9 years old and due for a replacement…tougher to find someone to do that than a landscaper this time of year and way more expensive than I imagined.