Rough and Discolored Pool Plaster - Why and how to fix?

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Still have another pound or two of CYA to dissolve.

Down 4ppm FC so added another gallon just now.

Stain is still about the same. What's interesting is that it's harder to see when the sun is out. If there is cloud cover the stain is much more pronounced and easier to see. If that helps anyone to identify.

Thanks
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
13,922
Houston, Texas
Did you lower your pH? If it is scale you may not see much difference until the slam is complete and you lower the pH to 7.0
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Did you lower your pH? If it is scale you may not see much difference until the slam is complete and you lower the pH to 7.0
Hi @zea3 ,
Yes, I lowered it to 7.4 before the SLAM... but that was almost a week ago.
Should I add any Muriatic Acid during a slam? I know the PH test won't be accurate but I'm sure it's high right now. Maybe add a third of a jug?
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
13,922
Houston, Texas
You should wait until the slam is finished, then drop the pH to 7.0 and keep it there for a few weeks to see if it is calcium scale. If it is calcium scale the lower pH will help the scale to release from the pool surface and go back into solution in the water. If you try to lower pH during the slam you'll just be chasing your tail trying to get it low enough.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
You should wait until the slam is finished, then drop the pH to 7.0 and keep it there for a few weeks to see if it is calcium scale. If it is calcium scale the lower pH will help the scale to release from the pool surface and go back into solution in the water. If you try to lower pH during the slam you'll just be chasing your tail trying to get it low enough.
Got it, thanks. If it is calcium scale, and I need to lower PH to 7.0 does that mean I'll need to re-plumb my system to bypass my heater?

Also, would scale just show up on one portion of the deep end of the pool and nowhere else?
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
13,922
Houston, Texas
Does the warranty on the heater require the pH be above 7.0? 7.0 is not aggressive and should not harm the heater.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Does the warranty on the heater require the pH be above 7.0? 7.0 is not aggressive and should not harm the heater.
You know... I'm not sure, I just thought I read that somewhere else on this site (low PH could affect the copper element and then you can get metal stains. Maybe that was for something else though). I'll cross that bridge if I get there.

I edited my post above to ask another question though...
Does scale typically show up in only one portion of the pool and nowhere else?
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
13,922
Houston, Texas
Scale deposits can start off looking like isolated stains here and there. If conditions are right, you can get all over scale formation where the whole pool is rough and discolored. If your stain was in a more accessible area we could have your try to scrape some off and test it with a drop of MA.

The pH becomes aggressive and damages copper when it drops down into the 6's or lower. We generally recommend our pools with high calcium run with pH around 7.0-7.2 to prevent calcium scale formation. This is important in areas with very hard water when a drain and refill will not drop calcium levels below 400 ppm. By keeping pH at the bottom of the acceptable pH scale for pools you can operate with higher calcium levels and not create scale. Once you get into extremely high calcium (over 800ppm) you will have to drain and refill to prevent scale.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Scale deposits can start off looking like isolated stains here and there. If conditions are right, you can get all over scale formation where the whole pool is rough and discolored. If your stain was in a more accessible area we could have your try to scrape some off and test it with a drop of MA.

The pH becomes aggressive and damages copper when it drops down into the 6's or lower. We generally recommend our pools with high calcium run with pH around 7.0-7.2 to prevent calcium scale formation. This is important in areas with very hard water when a drain and refill will not drop calcium levels below 400 ppm. By keeping pH at the bottom of the acceptable pH scale for pools you can operate with higher calcium levels and not create scale. Once you get into extremely high calcium (over 800ppm) you will have to drain and refill to prevent scale.
Great information @zea3 , Thanks.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Okay, well I overshot my CYA a bit (Maybe my pool is only 25k gallons and not 29k)... it's at 40 and my FC is at 16.

I'll continue this until I pass the OCLT and if I still have the stain I'll try lowering the PH and maybe getting a pumice stone.

I'll continue to update until I have some resolution.

Thanks everyone.
 
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Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Lost 2ppm FC last night... Stain is still the same.

I will continue to monitor throughout the day but seems likely that this will be the last day of my SLAM.

Assuming it is I will start monitoring PH as soon as I can and start to lower to 7.0 to see if that affects the stain.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Lost 1ppm FC last night (passed the OCLT)... Stain is still the same.

I will now start to lower PH to 7.0 and see if that helps the stain at all.
 
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Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
PH has been around 7 to 7.4 for a couple of days now. FC is drifting down to normal levels... Stain is about the same (It's been hot and sunny so it's harder to see). I tried to hit it with a pumice stone but that was tedious and I'm pretty sure did nothing. I'm still brushing regularly with a metal brush.

Now my union to my heater cracked and is leaking so I've got another project within a project. Man, pools are a lot of maintenance.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Did you ever try the ascorbic acid?
Soooo, before I do the full Ascorbic Acid treatment I should just buy some vitamin C... crush it up and put it in a sock and leave that on the stain for a bit first to see if it has any affect, correct? How long should I leave the sock on the pool surface for before I should see results and not damage the surface?

Thanks
 

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
2,292
Rancho Cucamonga, CA
Pool Size
18735
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45
From Pool School...

Place 15 to 20 Vitamin C tablets in a sock and crush them. Hold the sock on the stain for 3 to 5 minutes. If the stain vanishes or lightens then it is iron.
 
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Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Easier said than done in the deep end. I stuffed the sock in the tip of a pole and held it there for 5 minutes but it's really hard to tell if it did anything as the stain is a bit mottled and splotchy to begin with. Maybe I'll get a metals test kit... or, and I hate to even say it, take it to Leslie's down the street and have them test for metals.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Well, just had Leslie's test my pool water... the iron and copper were in range, but they said I need to do a phosphate treatment, lol (registered at 518). They had my PH at 7.3, which is pretty accurate, but I guess my stain is calcium scale. I'll keep my PH low for a bit and see if the stain reacts.
 

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