Strand discoloration to pool liner

[bergz22]

I have one spot on the bottom of the pool that is a brown and greenish spot. Hard to see in the pictures. I only use liquid chlorine in the pool. I've tried vacuuming it and brushing it multiple times. I just raised the pool to the slam level to see if that helps. CC show zero.

 

[JamesW]

It's likely to be iron.
Try putting vitamin C on a spot.
If vitamin C works, that confirms iron.
An ascorbic acid treatment will clear iron stains, but they usually come back over time.

 

[bergz22]

It's likely to be iron.
Try putting vitamin C on a spot.
If vitamin C works, that confirms iron.
An ascorbic acid treatment will clear iron stains, but they usually come back over time.

Use a vitamin c pill?

 

[JamesW]

Use a vitamin c pill?

Yes.