Brown Stains on Tile/Grout NOT UNDER WATER

[riskybizness]

Hi all - a newbie here to the forum and pool ownership, so please be gentle. Purchased a home with SW pool in November. Trying to get it ready and all is going well with pool balance, etc. However, we have an unidentified stain around the rim of the pool that will not respond to anything we throw at it (muriatic acid, ascorbic acid, brass and steel brushes...) We live in GA so we thought that perhaps the water level got too high at one time and caused that Georgia red clay to ooze out from under the deck. We also thought that the metal strip at the top of the tiles that meets the deck was rusting. I've attached pics for reference.. Any suggestions would be welcomed. Thanks in advance.

Tom
Atlanta - GA

 

[JohnT]

I'd have thought muriatic acid would have done it. It looks like the problem isn't as bad in areas where the coping covers the top of the tile. Does that hold true everywhere?