Black waterline ring

[Ke]

I lowered the water of my fiberglass pool a few inches in order to do some repair on the waterline tiles. Now that the repair is finished I notice a black ring around the waterline. I raised the water, did shocking and heavy duty scrubbing but nothing seems to help. Any suggestions?

 

[JasonLion]

Try a Magic Eraser or some tile soap.

 

[Ke]

I did try Mr. Clean's magic eraser, the black ring is on the fiberglass, not on the tile. Do I need to lower the water to use the eraser?

 

[frustratedpoolmom]

Has copper algaecide or copper based products been used in the pool?

 

[waste]

You also might try some baking soda on a kitchen scrubbie (you know, one side sponge and the other scrubbie) - apply the backing soda to the scrubbie side and see if that works in a test area.

 

[Ke]

I've not used any copper based products.

 

[Ke]

I finally used extra heavy duty kitchen scouring pad and it worked. Thanks everyone.