Stain around flood niche

[davelinde]

I just noticed a brown stain developing around the niche for my floodlight. It's got to be new in the last couple weeks since I'm sure it was not there when I was chasing after my pool leak.

For sure though we have changed things... this is the first two weeks we've been using the SWCG and we are still learning about how to dial in both ph and FC levels. Tomorrow I'll get the underwater camera out and get the latest water sample test results. For now... any likely suspects? I'm guessing the seal around the niche is not good and this is an iron stain from the rebar around it... but I've never done this before so that is a pure guess.

 

[JasonLion]

There is a simple test to see if it is an iron stain: hold a Vitamin C tablet against a stained area for 30 seconds. If the stain lightens or goes away around the Vitamin C tablet then it is an iron stain.

 

[davelinde]

...crud all I can find in the cabinet are multi-vitamins.
I sure didn't expect that to ever be a pool fixing issue!

 

[davelinde]

Publix values their vitamin C quite highly... So my daughter dove down and held the tablet on the stain and she said "it got lighter, for sure, mostly, I think so"
Pictures to follow once I figure out how to get them off the underwater camera.

So assuming this is iron, is my theory it's leaching from the rebar likely? Of all my pool subcontractors, who would own this and what is the fix? I'm thinking the pebbletec guy? Or maybe I just pull the light and skim coat the joint between the niche and plaster with pool epoxy and rub the rest of my vitamin-C bottle into the stain?

 

[JasonLion]

If there is any rebar near the surface in the niche that is a very plausible source. A part of the niche or light fixture made with inferior materials is another possibility.

 

[davelinde]

It's a hugely expensive pentair light so I'm not suspecting it... I think it's a hayward niche and it was all plastic and stainless steel IIRC. The niche was tied off to rebar before gunite but I remember making a point of snipping out all the bailing wire before plaster - still, for sure the bar is near the niche where it was tied. There is a layer of plaster over it because the niche had a collar of sorts to be a plaster ring and it's flush now. Odd...

 

[davelinde]

Pics still trapped in the waterproof camera... but DW called the plaster guy who said he'd look at it. His first reaction was that it will come off easily and should not return. I suppose that entirely depends on the source and I get the impression he's seen it happen before.

 

[davelinde]

The plaster guy hasn't gotten here yet, but oddly the stain seems to be fading by itself - for sure it is not getting worse. A different pool guy was just here and he said that we needed to watch ph levels and use a sequestrant. He suggested an acid injection system and said it was a very easy add-on. Considering it.