Markings on bottom of pool, stains?

[jweby]

Have these strange circular marking on bottom of pool. It didn’t respond to chlorine pucks or vitamin C. I’m guessing the plaster is old maybe? We just bought the house, so it could be age.

You can also see clear footprints in some spots, wondering if the old owner had a bad plaster job? It used to be a SWG pool, but they took it off as it was rented. After a shock is when I noticed the stains.

Besides these stains everywhere, the pool is great chemically as far as I can tell from the k2006C.

 

[ajw22]

The things you see are cosmetic and just typical of an old pool.

 

[JamesW]

Looks like copper.

Can you show me the system?

Can you show the whole pool?

 

[jweby]

The things you see are cosmetic and just typical of an old pool.

Okay that’s what I was wondering. Also I don’t know the age of the plaster, so was curious what are signs it needs redone.

 

[jweby]

Looks like copper.

Can you show me the system?

Can you show the whole pool?

Sure, I’ll grab a picture tomorrow when it’s light out. Pool is a rectangle with one side curved. Older pentair 1hp pump and sand filter. They work decent as far as I can tell. Water is crystal clear.

The house used to be an Airbnb, so not surprised if there was some loose change thrown in on accident.

 

[ajw22]

Okay that’s what I was wondering. Also I don’t know the age of the plaster, so was curious what are signs it needs redone.

Leaks or rust stains or gunite being exposed or delamination and chunks falling off or large cracks.

If the plaster is holding water then it is ok.

 

[jweby]

Sure, I’ll grab a picture tomorrow when it’s light out. Pool is a rectangle with one side curved. Older pentair 1hp pump and sand filter. They work decent as far as I can tell. Water is crystal clear.

The house used to be an Airbnb, so not surprised if there was some loose change thrown in on accident.

 

[JamesW]

It looks like copper stains.

The copper probably came from a gas heater as you can see a gas line in the picture.

They might have also used copper algaecides.

Get a stain ID kit to see what that shows.

Stain ID Kit | Jacks Magic

jacksmagic.com

 

[JamesW]

Note: Do not use calcium hypochlorite as that will make more stains where the chlorine makes contact with the plaster.

 

[Floridapoolguy34224]

Note: Do not use calcium hypochlorite as that will make more stains where the chlorine makes contact with the plaster.

Really? I have been using shock (calcium hypochlorite) to remove organic stains for a long time.

 

[JamesW]

Really? I have been using shock (calcium hypochlorite) to remove organic stains for a long time.

If you have copper in the water and green/turquoise copper stains, calcium hypochlorite can cause black stains as the calcium hypochlorite reacts with the copper.

 

[Floridapoolguy34224]

If you have copper in the water and green/turquoise copper stains, calcium hypochlorite can cause black stains as the calcium hypochlorite reacts with the copper.

Will a trichlor tab react with the copper and do that as well?

 

[JamesW]

Copper has two primary oxidation states.

Copper (I) is in the +1 oxidation state and copper (II) is in the +2 oxidation state.

Each state can form many different compounds, which are all different colors.

Chlorine can oxidize copper from the elemental state to +1 or +2.

As the state changes, the compounds can change.

Predicting the reactions is not easy and it depends on the ions in the water and what combines with the copper.

The compounds can be things like copper carbonate, copper (I) oxide, copper (II) oxide (black), copper sulfate, copper cyanurate (violet/purple) etc.

List of copper salts - Wikipedia

en.wikipedia.org