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

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Hi Pool Folks,

I've got an issue with my fairly new pool plaster. It's rough and discolored in approximately the area of the deep end where I always pour my chlorine and muriatic acid in (there is a return jet there).

My chems are on point now... but the PH was definitely high (purple) a few times throughout the winter and I've had to pour a bunch of acid in. My first thoughts are that maybe I poured in too much acid at once, close to a gallon, and even though I poured it in front of the return... maybe it was just too much, too fast and it did damage to the plaster.

We had a few really bad windstorms during the winter and there was a ton of debris on the bottom of the pool for a while and I wasn't able to clean it as quickly as I would have liked to... but when I did, that's when I first noticed the brownish blotches. I didn't know the patches were rough at the time, but just went swimming over the weekend and felt with my hand and they are definitely rough. Rest of the pool is good, it's just in about a third of my deep end.

I've tried scrubbing with a metal brush... but it does nothing, or very little at best. Sucks, cause the water is great and I just replastered the pool about a year and a half ago and this is really bugging me.

I've got a pic attached you might need to really zoom in on it to see but does anyone have any idea what I did wrong and how can I fix it?

Thanks All!
 

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ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
26,527
Northern NJ
Pool Size
35000
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Plaster
Chlorine
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Pentair Intellichlor IC-60
Place a trichlor puck on the stain for a few minutes to see if it lightens or removes the stain. If it does then the stain is organic.

 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Place a trichlor puck on the stain for a few minutes to see if it lightens or removes the stain. If it does then the stain is organic.

Hi Allen,

Thanks for the reply. I'll try it... so, just drop it in the deep end and position it with my pole?

I'd be shocked as I have 0 cc when when checking my chems and I scrubbed the heck out of it with a metal brush. Also, does the fact that it's super rough, only in the stained area, rule out organic?

Thanks
 

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
Hi Allen,

Thanks for the reply. I'll try it... so, just drop it in the deep end and position it with my pole?

Yup, how deep is your deep end?

Don't leave the puck on the plaster for too long as the acid in the puck can damage the plaster.
I'd be shocked as I have 0 cc when when checking my chems and I scrubbed the heck out of it with a metal brush.

You an have organic problems with CC = 0.


Also, does the fact that it's super rough, only in the stained area, rule out organic?

How big is the rough area?

Who widespread are the blotches?

It sounds like something dropped into the pool like tree sap.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
@ajw22
I wish I could be more precise with my answers but here it goes...

First, I left the puck in for about 5 minutes... did it twice but it's really hard to tell. I believe that I can see an outline of the circle from the time I tried it.

Deep end is probably 8-10 ft... it's pretty deep.

No trees that could have dripped sap, but maybe there was sap on the debris blown in from the wind?

The blotches are in about 1/3 of my deep end... not sure how much of it is rough as I just swam down there and started rubbing my hand over part of the area. When I felt rough patches I just assumed I had all the info I needed.

Maybe it is organic? I guess I should follow the instructions in that article and do SLAM, huh?

EDIT: Or should I just do an OCLT first as the water is already crystal clear and the cc is 0
 
Last edited:

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
Doing the SLAM Process is easy and non invasive and should be your first step. See what the chlorine consumption is and see how the blotches responds to a few days of high chlorine levels. Brush the blotches frequently and aggressively.

Let's see what happens.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Doing the SLAM Process is easy and non invasive and should be your first step. See what the chlorine consumption is and see how the blotches responds to a few days of high chlorine levels. Brush the blotches frequently and aggressively.

Let's see what happens.
Will do. Thanks for the help Allen.

Btw, should I use a regular brush or the metal brush?
 

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 can't get much pressure on a metal brush when that deep to do any damage. Might as well use it.
 
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sktn77a

Gold Supporter
May 16, 2010
2,139
Chapel Hill, NC
Try some ascorbic acid on the stain to see if it's metal (iron, copper). If you shock a metal stain, you can oxidize it and make it worse.
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Try some ascorbic acid on the stain to see if it's metal (iron, copper). If you shock a metal stain, you can oxidize it and make it worse.
Hi Keith,

Well, I'm knee deep in the SLAM right now.

Where do you get ascorbic acid? The pool store?

If I don't see improvement the day after tomorrow I'll get some and give it a try. What form? How do I apply it?

Thanks for the reply.
 

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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
Vitamin C tablets are ascorbic acid. Crush some up, put them in a sock, and let them sit on the stain for about 5 to 10 minutes. Below is an article from Pool School.

Best of luck!

 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Vitamin C tablets are ascorbic acid. Crush some up, put them in a sock, and let them sit on the stain for about 5 to 10 minutes. Below is an article from Pool School.

Best of luck!

Got it. Thanks!
 

Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
@ajw22
Just an update on this... seems a bit weird... I only lost about 2.5 fc overnight but I was gone most of the day today (9 hrs) and the fc went from 20 to 8.5. I don't think it was very sunny at my house today so not sure why it dropped so much more during the day than overnight.

I just re-upped the chlorine, brushed the heck out of the spot. I can see brown dust when I brush it but the blemish is definitely still there. Doesn't seem much better even though I see the brown dust when brushing. Hopefully it's okay to just let the Kreepy pick up what it does and I'll vacuum the whole pool in the morning.
 

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 lost enough FC to say you have something going on in the water.

The brown dust shows something is loosing up.

So I would continue the SLAM Process. These things take a while.
 
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Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Well, day 3, maybe some improvement... definitely not worse so I guess I can rule out a metals stain.

But man... if that's sap, it's really tough cause I've been scrubbing the heck out of it with both a regular and metal brush all day today. I ran out of the reagent to test FC as I didn't realize how much I'd use on a SLAM but refill will arrive tomorrow. I'm just eyeballing the chlorine for now but erring on the side of too much instead of too little.

Will post another update tomorrow.
 
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Palpatine

Bronze Supporter
Sep 3, 2019
250
West Hills, CA
Hmmm, day 5, honestly don't see much improvement yet. Getting a bit discouraged if I'm being honest. Is there any more aggressive measure I can take... granules maybe?
 

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
What ado you think granules are going to accomplish?
 

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