VitC test leaves a trail of brown

[Davey_crocket]

Hi folks,

Trying to figure out some stains in the pool, I chucked some acetic acid in some skimmer socks and put them on the stained area in the deep end of the pool.

5 minutes later I notice something very strange, there is a streak of brown coming from where the socks are. Any ideas what this might indicate?

 

[JoyfulNoise]

Ascorbic acid, I hope … hopefully pure VitC powder or tablets and no additives to it.

When AA causes stains darken it is indicative of the stain being copper. Are those dark trails easily brushed away? Have you been using any pool products with copper in them?

 

[Davey_crocket]

Yes pure powder, have made the mistake of using orange vitc tablets in the past. They don't really brush away but do lighten a bit, running the pump now to see if they lighten up.

I was thinking copper but the brownness of the stain as opposed to grey put me off.

It hasn't had any copper since I bought the house 2ish years ago, but the previous owner did use the cheapest stuff he could find.

Could have had some fresh metals come in through salt around march, we had a national shortage so had to go with a different brand to usual

 

[JamesW]

Looks like copper and maybe some silver.

Do you have an ionizer?

 

[Wobblerlorri]

Davey,

You said in your original post you "chucked some acetic acid" in your socks. Was it acetic acid (aka white vinegar) or ascorbic acid (vitamin C)? I don't think vinegar will do much for your pool's surface...

 

[Davey_crocket]

Davey,

You said in your original post you "chucked some acetic acid" in your socks. Was it acetic acid (aka white vinegar) or ascorbic acid (vitamin C)? I don't think vinegar will do much for your pool's surface...

Sorry ascorbic, pure vitamin c powder

 

[Davey_crocket]

Looks like copper and maybe some silver.

Do you have an ionizer?

Nope just a swcg

 

[JamesW]

Has copper or silver algaecide ever been used?

What color was the original plaster?

You might need sulfamic acid to clean the stains.

And then a drain and refill if it's safe to do that without floating the pool.

 

[Davey_crocket]

Hi James,

I've never used a metal based algaecide in it but the pool was 2yrs old when we bought the house, I do remember there being a bottle of algaecide left in the pump enclosure.

The original color is a good question, it's white with a blue and white quartz speckle by the looks of things, but the pool has always had patches that are greyer than others whilst I have lived here.

 

[Davey_crocket]

This is the step back in 2020

 

[JamesW]

Probably copper stains.