Hydration Stains?

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,847
Pleasanton, CA
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
Here is some really good information on plaster issues:

 

Bevgrat

Member
Nov 14, 2020
16
North Port Florida
Bevgrat, welcome to Trouble Free Pools :)

Sorry to hear about these problems. So you fill with well water, right? Do you know if you have metals in your water? I'm sorry to say we've never heard of particularly good results with the CUlator.

What is your current chemistry and are you testing yourself or relying on a pool store? Can you tell us:
FC
CC
pH
TA
CH
CYA
Salt level

What other chemicals have you or the pool builder put in your pool??

A thread that discusses hydration stains-

Maddie :flower:
I really don't know exactly what it is.

I would try sulfamic acid, but I don't know if it will work.
I really don't know exactly what it is.

I would try sulfamic acid, but I don't know if it will work.
[/
I really don't know exactly what it is.

I would try sulfamic acid, but I don't know if it will work.
Ok, I thought that the cartridge would be green. It looks pretty clean.

The only thing I can think of to try is sulfamic acid.

Jack's No 2 is sulfamic acid.


Note: I don't mean sulfuric acid.
I really don't know exactly what it is.

I would try sulfamic acid, but I don't know if it will work.
We are thinking this might be the issue.
Plaster Discolorations – New white pool plaster can discolor (darken or turn gray) from adding excessive calcium chloride set accelerator, from late hard troweling, from thin and thick areas due to an uneven shell, etc. Gray (or grey) mottled discoloration (also known as “water entrapment” or “hydration”) is smooth to the touch and difficult to lighten, may be remedied by acid washing, sanding, or torching the surface, but these processes are generally detrimental to a plaster finish and the discoloration often returns later. Late hard troweling can cause “trowel burn” which darkens the plaster color in localized areas. Severe mottled color variation from calcium chloride or finishing issues may occur quickly once filled with water, or take several months to become visible.
 

JamesW

TFP Expert
Mar 2, 2011
21,937
The turquoise green points to copper. So, that's why I suspect copper.

If you can't figure out any other solution, I would try sulfamic acid.
 

JamesW

TFP Expert
Mar 2, 2011
21,937
Try dropping some vitamin C tablets on a spot and leave them there for at least an hour.

Also, try dropping a little bit of calcium hypochlorite in a different spot to see if it makes a black spot. Don't leave it there for more than a minute before brushing it away.
 

onBalance

TFP Expert
LifeTime Supporter
In The Industry
Jul 25, 2011
1,081
Utah
While the photo of the pool (at a distance) does look like copper staining, the close-up photo appears to show that it is discolored plaster. But the pattern of the discoloration is somewhat unusual.
Given that this pool was drained, torched, and acid washed by the pool builder indicates that the discoloration is not copper staining, but instead, would indicate that it is likely a form of gray mottling discoloration or perhaps bad and contaminated cement material.
The below posts discusses gray mottling discoloration.
 
  • Like
Reactions: JamesW

onBalance

TFP Expert
LifeTime Supporter
In The Industry
Jul 25, 2011
1,081
Utah
A good question that I should have addressed above.
Gray mottling discoloration of the plaster goes deep and below the immediate surface. If sufficient power sanding is performed to remove about 1/8 of an inch of plaster, then it is possible to restore the original white color. If the cement was bad, then sanding would be fruitless. Stain treatments do not work with either of these two problems. Torching works temporarily, but damages the plaster, and the discoloration usually returns. Acid treatments are detrimental also.
 
  • Like
Reactions: JamesW

Bevgrat

Member
Nov 14, 2020
16
North Port Florida
While the photo of the pool (at a distance) does look like copper staining, the close-up photo appears to show that it is discolored plaster. But the pattern of the discoloration is somewhat unusual.
Given that this pool was drained, torched, and acid washed by the pool builder indicates that the discoloration is not copper staining, but instead, would indicate that it is likely a form of gray mottling discoloration or perhaps bad and contaminated cement material.
The below posts discusses gray mottling discoloration.
So you are basically telling me no chemicals will remove this therefore we’d have to get it replastered?
 

JamesW

TFP Expert
Mar 2, 2011
21,937
So you are basically telling me no chemicals will remove this therefore we’d have to get it replastered?
I think that they are indicating that sanding might help or you would need a replaster.

I would try sulfamic acid even though it is not likely to work.
 

Bevgrat

Member
Nov 14, 2020
16
North Port Florida
A good question that I should have addressed above.
Gray mottling discoloration of the plaster goes deep and below the immediate surface. If sufficient power sanding is performed to remove about 1/8 of an inch of plaster, then it is possible to restore the original white color. If the cement was bad, then sanding would be fruitless. Stain treatments do not work with either of these two problems. Torching works temporarily, but damages the plaster, and the discoloration usually returns. Acid treatments are detrimental also.
We are hearing salt generator might be causing issues, could that affect the plaster? What are your thoughts on painting the pool? This started 6 months after the installation and pool installer contract states not responsible for discoloration etc. After spending $$$$ on a pool and then to have to have it replastered just sickens us and scares us that it could happen again.
 

JamesW

TFP Expert
Mar 2, 2011
21,937
It's not the salt system.

Paint is horrible.

I think that your options are drain and sand or replaster.

I would try sulfamic acid.
 

Bevgrat

Member
Nov 14, 2020
16
North Port Florida
We are hearing salt generator might be causing issues, could that affect the plaster? What are your thoughts on painting the pool? This started 6 months after the installation and pool installer contract states not responsible for discoloration etc. After spending $$$$ on a pool and then to have it replastered just sickens us and scares us that it could happen again.
If we have it replastered could it bleed through if they don’t chip out the old plaster?
 

Bevgrat

Member
Nov 14, 2020
16
North Port Florida
A good question that I should have addressed above.
Gray mottling discoloration of the plaster goes deep and below the immediate surface. If sufficient power sanding is performed to remove about 1/8 of an inch of plaster, then it is possible to restore the original white color. If the cement was bad, then sanding would be fruitless. Stain treatments do not work with either of these two problems. Torching works temporarily, but damages the plaster, and the discoloration usually returns. Acid treatments are detrimental also.
If we have it replastered will the grey mottling bleed through or will we have to have it chipped out.
 
Last edited by a moderator: