Apparent tie wire stain on white plaster

[nightswimming]

Hello folks,
The spot is about halfway down past water line on wall. Carefully chipped out a 1/4" depth/ neat lines. 2" x 3" roughly.
I tried to patch it underwater last fall with no success. (patch would not stay/ dissolved)
EZ Patch 1FS

Have experience finishing concrete and using hand trowels/floats. Feel somewhat comfortable being able to install the patch.
Plan now is to drain down to expose to air and patch, let dry for a day or two, fill er back up.
Have separate pump that I can run - drain suction to water features to get some circulation during the drain down.

Any direction would be much appreciated.
Thank you.

 

[Texas Splash]

@AQUA~HOLICS was just speaking about this earlier this morning with another member. Do you have a pic or two you could share?

 

[nightswimming]

First pic upload so not sure about my ability to follow protocol.

After chipping out last fall it I chased it to a very small spot, since it has gotten uglier, assume I'll have to chip it over a little more.

 

[ajw22]

You have to cut out the rusting rebar and then patch the hole with hydraulic cement. Then plaster over the hydraulic cement.

The stain will return if you just plaster over the rusting rebar without removing it.

 

[nightswimming]

ajw22,
Thank you for your reply.
The spot was initially on the far opposite side of where it is now, so I chased it to where it is now last fall. A few weeks ago it was significantly smaller.
Having a hard time understanding how it is anything other than a tie wire sticking out to far from the gunnite into the plaster.
Sounds like I may be in for more than I bargained for.

 

[Texas Splash]

Do you have any pics of the pool during construction?

 

[nightswimming]

This pool/plaster is over ten years old.
Excavation was into sandstone iron ore rock for the most part. We have had no issues other than the recent stain on the plaster.
A replaster is obviously in future, just trying to
hold off on that for the short-term.

 

[ajw22]

I don’t speak Texan and don’t understand how you chase a stain.

Where is the far opposite that the stain was? What is there now?

Have you rubbed a paste of Vitamin C on the stain to confirm it is iron rust?

That stain look too big to be a rusting rebar stain.

 

[ajw22]

Can you pinpoint on the rebar pics where the stains are?

 

[nightswimming]

Wow. Okay.
When I initially gently chipped into the rusty colored stain (underwater) I followed the rust to the left ( no rust at initial spot, it moved laterally to the left during the chipping, as a piece of tie wire would react) so I referred to this as chasing the rusty spot. It moved as I chipped.
I ended up with just a speck and thought it would be prudent to place the patch. If for no other reason to reduce the exposed very small speck of rust to the water.
So based on my pic of the spot, it was initially on the opposite side of the current spot.

 

[ajw22]

Now I understand. The rust stain will flow from the source until it shows itself. The rusting area may not be directly below the stain.

You will need to dig into the gunite until you find the source of the rust. That may be anywhere around where the stain is visible.

Then cut out the rusting steel back to clear steel. Your pool will never miss one piece.

Then plug the hole with hydraulic cement and plaster over it.

 

[nightswimming]

Understood, thank you.
Is the patching material I have for the plaster suitable?
How long for the patch to cure before refilling?(other than manufacturers recommendations)

Thanks again for the comments.

 

[AQUA~HOLICS]

Only other suggestion is to spray paint what ever rebar or ties that are exposed with a rust-oleum paint prior to patching.

 

[ajw22]

Is the patching material I have for the plaster suitable?

I find the regular EZ Patch plaster easier to work with then the Fast Set if you can drain down and expose the area to be patched.

The FS is difficult to hold together and get packed in and smoothed when underwater.

How long for the patch to cure before refilling?(other than manufacturers recommendations)

24 hours is fine.

 

[nightswimming]

Good point. I no longer need the FS, which as you stated was difficult to work with.
Thank you so much.
Hoping to drain down overnight, patch and cure, then fill it up before water gets funky.
Planning on stiffening my water up before drain down to avoid algae etc.

 

[nightswimming]

Thanks to all who replied.

 

[nightswimming]

Update.
I scored a square area around the patch and removed the very small rust vein to about 1/4-3/8" with a dremmel tool. (This method worked great)
Then patched with the aforementioned product on May 28th, and refilled the pool 24 hours later.
So far no sign of rust.

 

[Texas Splash]

Then patched with the aforementioned product on May 28th, and refilled the pool 24 hours later.

Great! What did you use for the patch? Hydraulic cement?

 

[nightswimming]

No sir, EZ patch.