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

ajw22

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TFP Guide
Jul 21, 2013
26,527
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Keep your CSI in the 0.0 to -0.30 range.

To get rid of calcium scale drive your pH and CSI lower.

Lower your pH to 7.0 and try and maintain it there. Your CSI may get down to -0.6 or even -1.0 for a while to dissolve the scale.
 
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Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
I just wanted to update this thread...

I've been keeping the pH between 7 to 7.4 and keeping the chlorine pretty low... but the scale is getting worse and it's spreading. I guess I'll just have to deal with it this summer and maybe drain and acid wash the pool next year unless anyone has any other suggestions for me.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
26,527
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
You PoolMath logs have not been updated in 10 months.

Post a complete set of current test results.

What is your CSI with your pH at 7.2?
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
You PoolMath logs have not been updated in 10 months.

Post a complete set of current test results.

What is your CSI with your pH at 7.2?
FC 8
CC 0
CYA 50
pH 8ish
TA 70
CH 570

CSI .44 (currently)
CSI -0.32 (if pH were at 7.2)

Crazy that the pH is so high as I've been monitoring and for the last week and a half it hasn't been above 7.4... but I did just put a gallon of chlorine in about 2 hrs ago.

I put a half gallon of muriatic acid in just now because of the high pH and will check pH in a couple of hours to make sure.
 

Bperry

Gold Supporter
Aug 20, 2020
606
Knoxville, TN
Pool Size
27000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60
FC 8
CC 0
CYA 50
pH 8ish
TA 70
CH 570

CSI .44 (currently)
CSI -0.32 (if pH were at 7.2)

Crazy that the pH is so high as I've been monitoring and for the last week and a half it hasn't been above 7.4... but I did just put a gallon of chlorine in about 2 hrs ago.

I put a half gallon of muriatic acid in just now because of the high pH and will check pH in a couple of hours to make sure.

PH is 8-ish? Meaning its off the scale too high? Or between 7.8-8.0?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
26,527
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
So your CH rose by 200 ppm in 10 months. You will need to drain your pool to lower your CH sometime in the next year.

What is the CH of your fill water?

Marty may have some ideas on how to manage your water chemistry @mknauss
 

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Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
So your CH rose by 200 ppm in 10 months. You will need to drain your pool to lower your CH sometime in the next year.

What is the CH of your fill water?

Marty may have some ideas on how to manage your water chemistry @mknauss
I did add calcium during the startup... and at another time but I don't have the records.

I'll check my fill water for CH but I think it's around 350ish... but I'll post shortly after I check pH again.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
42,043
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
With fill water at 90 CH, you should be pretty good for some time. Try to use rain water to refill pool when you get.

I would suggest starting to use CSI for chemistry monitoring as your current CH is getting on the higher end of the normal scale.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
With fill water at 90 CH, you should be pretty good for some time. Try to use rain water to refill pool when you get.

I would suggest starting to use CSI for chemistry monitoring as your current CH is getting on the higher end of the normal scale.
Thanks for your response @mknauss . We don't get a lot of rain where I'm at and it gets pretty darn hot. I already fill about 5 min of water (line goes directly to the pool) about once every 2-3 days.

Do you think I'm fine where I'm at? The scale (stain on the bottom of the pool) seems to be getting worse and it's spreading. I'll stay on top of the pH and CSI but do you think I'd be better of doing a partial drain?

Thanks
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
42,043
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
At a CH of 570 (how did you test that? Normal results are in factors of 25) you are not in scaling region. If you drained, the lowest the CH should go is 350 ppm. So your stain is not likely to be scale, unless your test results are not accurate.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
At a CH of 570 (how did you test that? Normal results are in factors of 25) you are not in scaling region. If you drained, the lowest the CH should go is 350 ppm. So your stain is not likely to be scale, unless your test results are not accurate.
I just used the regular CH test, filling comparator tube to 25ml... I should probably start only filling to 10ml for the "high" anticipated calcium test in which case it says to multiply drops by 25 instead of 10. Just for a point of reference, I took a sample to Leslie's the other day to test for metals and they measured my my calcium at 458.

My test results should be accurate... I don't see how I could have screwed them up.

What else could the stain be? I slammed my pool a couple of weeks ago and I believe I had ammonia as my CYA was at 0... but metals were in range and my pool is holding chlorine now.

I'm really at a loss here.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
42,043
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Have you tested the stain with Vitamin C? A trichlor puck?
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Have you tested the stain with Vitamin C? A trichlor puck?
Yup and yup. At first I thought the trichlor puck worked... but the slam didn't seem to help the stain. The vitamin C test is not easy to perform in the deep end but I didn't see any results... and the Leslie's metals test showed iron at .1ppm and copper at .2ppm.

You're thinking it could be organic, even though I passed the OCLT and water is crystal clear?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
42,043
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Unsure. Did you have high CH and/or high pH in the past that might have created the scale? Scale can form with dirt or other organics in it and look like a stain. But the puck should have lightened it as it is acidic and would cut through the scale.
 

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