Plaster Longevity and Cleaning

Timmy_C

Member
Jun 2, 2020
14
Tempe, AZ
Hi all,

I have a pool at my home where I’ve been told the plaster was redone approximately 10 years ago. It needs a water change and it has some staining so I was researching my options and also discussing with a local pool servicer. This person said that I should not do an acid wash because it will cause the plaster to fail in a year or so since new plaster is less durable than the plaster of old.

Is this true? Should I avoid an acid wash due to old plaster? If yes, any other options I should consider?

Concerning the staining, testing is pointing to calcium staining due to old water possibly mixed with some metal staining. It will come off with a pumice stone but it takes some work.

Thank you,
Tim
 

HermanTX

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May 20, 2020
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Katy TX
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Is your plaster just stained or is there any chips in it? Do you happen to know what type of plaster was installed 10 yrs ago? Is it also just white standard plaster or is a pebble type of plaster?
 
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Timmy_C

Member
Jun 2, 2020
14
Tempe, AZ
I do not know any specifics regarding the plaster that was installed 10 years ago but it’s definitely standard white plaster. There are a few small quarter sized spots on the side where the plaster is degrading (not really chipping). Primarily it’s just stained. I have some citric acid left over from an attempted stain removal last year so I was going to try this again prior to draining. If you click on my username, you can see my thread from last year which includes pictures of the stains, things still look the same.

Something I should also mention is that I know I have very high calcium levels. Is it a bad idea to try citric acid with high calcium? I realize it will likely form precipitates but my thought is I would then pump it out. Perhaps I’d be better off trying the citric acid treatment with new water rather than old water? I do believe some of my staining is due to metals, both iron and copper.
 
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mknauss

Mod Squad
TFP Expert
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May 3, 2014
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Laughlin, NV
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Your other thread you were getting replies concerning copper staining. Realize that if that is true, and you use the citric acid, the staining may get darker. Sulfamic acid is used to remove copper stains. Though in general they are hard to remove.
 
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Timmy_C

Member
Jun 2, 2020
14
Tempe, AZ
Added a few pics as I’m in the process of draining. Not surprisingly, the citric acid didn’t have an effect. The 10-year old plaster appears to be in very good shape. The discoloration seems to be primarily scale.

Should I attempt an acid wash to see if it has any effect on the scale? Consult a professional? Or just fill it back up?

Note I’m primarily draining due to 10-year old water with high levels of calcium, CYA and TDS. So my primary goal is new water but a renewed appearance would be nice too since I am bothering to drain.
 

mknauss

Mod Squad
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May 3, 2014
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Laughlin, NV
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Acid wash will degrade your plaster and lessen its life by a substantial amount. I would suggest only a person whom knows how to manage an acid wash should perform that. Though TFPC does not endorse acid washing to remove scale.

We suggest you maintain a negative CSI (-0.6 to -0.3) and brush often to slowly remove the calcium.
 

Timmy_C

Member
Jun 2, 2020
14
Tempe, AZ
It’s good to know TFPC does not endorse acid washing to remove scale, most things make it sound like acid washing is as commonplace as cleaning your filter basket!

I think I’ve decided that I’m going to simply change the water and continue maintaining a negative CSI. I did attempt to maintain a negative CSI previously but it did not seem to make a difference in removing my scale but perhaps new water will yield better results.

Thank you for the guidance! I appreciate it!
 

mknauss

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Laughlin, NV
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I did attempt to maintain a negative CSI previously
Hate to point out your only saved test results in Poolmath had a CSI of 0.76 ------------------
 

Timmy_C

Member
Jun 2, 2020
14
Tempe, AZ
I appreciate you looking at that but I wasn’t updating Poolmath after my initial entry nine months ago. I’ve been keeping a manual log and when I checked those numbers in Poolmath all indicated I would have had a negative CSI as I’ve been keeping pH low. This scaling occurred during a three month span prior to me purchasing the house where the pool was at a pH of 8 and the walls were not being swept. I made considerable progress in removing scale with a negative CSI but then progress stalled three-four months ago.
 

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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
41,988
Laughlin, NV
Pool Size
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Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Any chance you have a water softener at your home? After you change your water out, if you can use soft water to fill up the pool due to evaporation, you are better off.
 
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