Stubborn Orange Stain on Tile Wall

[zollan23]

Hi everyone -
My pool has an 18" raised wall on one side (leads into a raised spa) and earlier this week I noticed an orange stain on the tile. The tile is mostly white/grey so it stands out quite a bit. I took a regular pool brush to it and it had no effect on the stain at all.

Curious if anyone has an idea of what this is and recommendations on how to clean it?

Pictures attached.

Thanks,

JZ

 

[JamesW]

Probably iron.

Crush up some vitamin C, make a paste and scrub with a brush.

 

[JamesW]

It's probably a form of efflorescence, which is where water bleeds through a wall or deck and picks up minerals like calcium, iron etc.

Most likely, there is iron rebar in the wall that is rusting and creating a source of iron that colors the efflorescence.

 

[zollan23]

Super interesting. There is definitely rebar behind the wall so that would make sense. Supposedly, the builder put an anti-rust protection on it but who knows. Will try the vitamin C trick so thank you.

 

[zollan23]

Alright, guys. I tried the crushed vitamin C and before/after is attached. Hard to tell much of a difference. Anything else that is recommended I try?

 

[mknauss]

CLR. Try it in an inconspicuous spot on that material that covers that wall first.

 

[duraleigh]

Vitamin C and then CLR make good sense. If they both fail, i would then suggest a 50-50 mix of muriatic acid and water.

You would do best to use an acid proof cloth but an old rag (it will get ruined by the muriatic) can do.

Wear rubber gloves and DON'T SPLASH.

Whether it works or not rinse all pool tiles when finished. Your grout will foam up (probably).

Don't be shocked if it comes back and you have to do it again.

 

[zollan23]

Thanks again as always.... Will report back

 

[JamesW]

If it's iron from rebar, it will just keep coming back until you figure out why water is bleeding through the wall or you deal with the rebar.

 

[JamesW]

Oxalic acid or sulfamic acid might work but they are more hazardous and they might damage the stone.

What is the stone type?