Unusual Stain In Tile Grout

[bxcrwlly]

Last week I noticed a strange stain appearing in the tile grout in the area of the spa spill-over into the pool. In the past I would see an occasional calcium build up in this area but never anything as depicted in the photo. The color is a reddish-brown. I removed most of it with muriatic acid over a week ago and it's back as of yesterday. Pool has been maintained at balance. This is the only location in the pool I see such an occurrence. Appreciate any input or ideas.

 

[Patrick_B]

Sorry, I can't help but perhaps someone has seen the same of similar.

 

[kimkats]

Does if "feel"? As in is it slimy? Is it built up? Is it just color?

Interesting that the acid made it go away but then it came back. Have you tried putting bleach on it? Just brain storming to see what helps.

Oh just had a thought. Does it look like rust? I wonder if there is a piece of rebar RIGHT there close and.......

Let us know what you see/feel.

 

[Casey]

Is this the only area it's happening in?

 

[bxcrwlly]

Kimkats: Doesn't feel slimy. Just a rust colored stain.

Casey: Yes, this is the only area it's showing. Exactly the same location where we use to get a calcium build up from the spill-over.

 

[duraleigh]

While the efflorescence I have seen has always been white, I suppose there is no reason it can't be brown as well.

If it is efflorescence, (migrating from below the surface) your only path is to keep removing it with muriatic until it stops.

 

[bxcrwlly]

Thanks Dave....will continue applying MA periodically and post an update on any changes.