Grey spots on bottom and sides of plaster pool

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S

sandeeret

0
Oct 4, 2016
10
Yulee, FL
I have been fighting these dark/light grey spots in my pool all summer. Before I found this site, I was using my local pool store and their advice. :( They told me that I had black algae and I have been following their procedures for removing it (algaecide). It has done nothing to the spots. I found your site and ordered my test kit. About 2 or 3 weeks ago, I SLAMed my pool for a week. No difference in the spots. I did the puck spot test and there was no change. I tried the vitamin C test on one of the spots and again no change. I am not sure what I am dealing with here. Can someone offer up some help? Pool is just turning one year old this month (Nov), it is a plaster pool with Diamond Brite finish.

My numbers:

FC 2.5 CC 0.5
pH 7.6
TA 80
CH 320
CYA 55
 
Here is a pic.

omWIkdC.jpg


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pooldv said:
Are the spots rough and raised above the plaster surface? Or smooth?

If rough it could be calcium scale, especially if the PH spends some time above 7.8 pretty regularly. More here, Pool School - Calcium Scaling

If smooth it could be hydration. More here, Diagnosing Pool Plaster Problems

It doesn't sound like black algae, more about that here, Pool School - Black Algae
Click to expand...

They are smooth. They kind of look like they are actually part of the marcite. I tried scrubbing one with a pumice stone on my pole and it didn't seem to do anything, but I do see a lighter area around it where I scraped with the pumice and got the marcite.
 
Yep, looks like copper. If you're using copper algaecide, that's going to happen.

I think that you have turquoise staining everywhere and the spots are where the copper is being oxidized into a new compound.
 
JamesW said:
Yep, looks like copper. If you're using copper algaecide, that's going to happen.

I think that you have turquoise staining everywhere and the spots are where the copper is being oxidized into a new compound.
Click to expand...

Is there something I can do to get rid of the spots? Do I need to replace the cartridge (only a year old)? I have stopped using the algaecide that I apparently didn't need in the first place. I don't know where I go from here.
 

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You might be able to use some dry acid in a sock or Muriatic acid through a tube to remove the stains. Then if there is sequestrant in the water it should prevent re-staining for a while but it will need to be added regularly before stains reappear. Or try removing the stains with sequestrant in the water and then drain the water to get the copper out of the pool. But, it is all kind of iffy on how well it will all work. It is very difficult to remove copper from the pool.
 
How wide spread is the staining? If the staining is wide spread, then your only option is to engage in a stain removal program, then dump the water and refill. See this thread from a fellow that ruined his newly plastered pool by listening to the "sage advice" of a friend who told him to dump root killer (copper sulfate) in his pool -

Copper Sulfate usage???

Unfortunately the original images are no longer available but the stains in his pool were very extensive. The upside of the story is that he contacted Jack's Magic Inc (a supplier of stain removal chemicals) and he was able to identify the stain and order the necessary chemicals to remove the copper staining. After the stains were lifted, he dumped his pool water and refilled. The plaster looked brand new again.

You might look into Jack's Magic products and call their help line. They are very knowledgable and they can help you to identify what the stains are (copper most likely) and how best to treat them.
 
Sequestrants, like Jack's, will bind the metal in the water and prevent it from depositing on the pool surface as a stain. It won't pick up metals from stains already deposited.

You would need to use dry acid in a sock or Muriatic acid poured through a tube onto the stain and brushed to try to lift the stains.
 
There is another possibility for the cause of those spots, and independent from the copper issues.
Sometimes while plastering a pool, some small or partial leaves fall in, and gets covered up just slightly by the plaster material, but very close to the surface and not seen by the troweling (finisher) person. Over time, the leaves decay and turn (discolor) the plaster a slight brown color in those spots.
Generally, there is nothing that can remove that type of discoloration problem.
 
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