Help with Pool Stain

[arin]

Woke up yesterday to this stain. Assumed it was organic so I pushed CL to shock level (CL31, PH7.6) but the stain isn't going away. Always used TFP pool method so never introduced any metals. Any suggestions on how to remove it?

 

[JamesW]

It's probably iron from something iron sitting on the surface.

Is it on the wall or floor?

Try ascorbic acid (vitamin C).

If it goes away and comes back, it's probably coming from in the plaster from a wire tie or rebar.

 

[arin]

Thank you for the quick response. This is the only spot and it’s located on the pool floor in the middle of the pool.

 

[JamesW]

Probably something iron fell in the pool.

Did you cut metal or have anything metal that could have gotten into the pool?

 

[arin]

Haven’t done anything with metal by the pool. When I first found it I went to broom it and noticed a light brown saturated marble sized ball of something sitting over the darkest point of the stain but once I broomed it that disappeared. That’s what made me think it was organic so I pushed the CL to shock level, but it hasn’t gone away with 24hrs shock. How do I apply an AA treatment to see if it’s iron?

 

[JamesW]

Crush some vitamin C and sprinkle the dust on the spot.

Put the vitamin C in a sock or cloth to help it stay together.

 

[arin]

To follow up I tried crushed vitamin C in a sock and it seemed to lighten the stain so I proceeded to neutralize the CL move PH down to 7.2 and treat the pool with ascorbic acid. Unfortunately the ascorbic acid didn't work so I had the pool builder come out and they verified that it is something in the plaster, wire or rebar so I am proceeding forward with a repair from the pool builder. Any information on a proper repair would be helpful and again thank you TFP for being being a solid resource.

 

[JamesW]

You have to chip out the section to remove the metal and then cover it with something that will set up under water.