Need Input From Stain Experts!!!

Skyline

Active member
Jun 17, 2016
35
PA
Greetings everyone!

I am experiencing some staining problems and hoping some experts can offer their opinions and advice.

I opened up the pool this year to a very noticeable stain ring around the pool where the water level would have been over the winter. This also happened last year too. I'm trying to figure out exactly what is going on here, so all input will be appreciated. Please see attached pictures of this stain ring.

Opening 1.jpg

Opening 2.jpg

A quick back history... We had our 50 year old pool (that we inherited when we bought our house a few years ago) plastered with Diamond Brite in mid September, 2019. The pool was fully sandblasted down to the original concrete (which I was told was Shotcrete), all cracks were filled-in and then it was bond-coated right before plastering. We also had the attached Spa I built plastered at the same time.

The pool is about 34k gallons, and the spa is about 1k gallons. I had 5k of water trucked-in to expedite the initial filling. The rest was from our city tap water. I added one or two bottles of Jack's Magic just because I read here on the forum that it is good practice in case there are any metals in the water. (Our city water has a low copper level on their reports, btw.) The pool filled-up with a greenish tint to the water, but the spa was great. I panicked and called the PB, who said that was normal for a first time fill. So I waited it out a few days and the water cleared up perfectly. I did everything needed over the next two months (perfect levels, brushing, vacuuming, etc and closed in mid-to-late November, trying to give enough time for the new plaster. I closed everything at the right levels, and didn't add anything except maybe a bottle of Polyquat 60 but I am not 100% sure on that. I have a gas heater hooked-up, but did not use it till the following year. I also have a SWG, but did not install it till the following year.

Initial Fill 1.jpg

Initial Fill 2.jpeg

Over the winter, some of the water bags lost hold of the solid cover and it got slightly pulled into the pool. Some leaves, twigs etc. were in the pool when we opened it last year in mid April. The water was algae green which cleared up in a week with shock level chlorine, but the pool itself still looked great except for a stain ring more or less what I opened with this year. Also, there was a lot of scale all over the surface, and of course the pH was very high, which was understandable because it was just plastered.

I came to the conclusion (not sure if it was correct or not) that it was calcium scale staining. Mostly because I had no idea how that much metal would have gotten in the water so soon to be metal staining, and because the staining was only in a ring right where the water level would have been while the pool was closed, and not anywhere else on the pool surface. Also, neither Vitamin C tablets nor chlorine pucks had any affect on the staining.

So I simply maintained a target CSI of around -0.8 (keeping the pH close to 7.0) to help slowly descale the pool and increased the chlorine level to about 75% of shock levels to remove staining. I brushed the stain ring and the whole pool everyday. It took a good two months or so, but the staining completely disappeared. I then put all the levels back to target and kept them there till I closed the pool last year. I didn't do any special stain chemical treatments and I didn't add sequestering agents either. I didn't even think about that because I didn't think it was even metal staining; rather I figured that the staining was organic-based, and that once all the staining was gone that it was a done deal. I installed the SWG and added salt after the stain was gone.

At the end of last year before closing, I made sure all levels were perfect, added a bottle of Polyquat 60 and closed her up.

This year was basically a repeat of last year. But I didn't want to take 2 months again to get rid of the staining. Plus I'm not 100% sure it is/was organic scale staining, so after some reading I did the Metal Magic sponge test which worked amazingly and completely removed the staining within 5 minutes. I then followed it up with a Metal Magic treatment. I only used 4 bottles, which was what was described for light staining for my size pool. I thought that would be enough because of how fast it removed the stain with the sponge test, but it only removed about a 1/3 of the staining. I did another treatment, and I'm at about 2/3 reduction in staining.

At this point I thought it would be completely gone. I used one of the stain ID kits.to see if I could see what the staining truly is because I'm not so sure what it is now. Iron had no effect, but the Copper & Scale test worked best. So I guess it's copper, or copper & scale, or scale with organic stains embedded in it like I've been suspecting this whole time.

Just out of curiosity, I did a sponge test with muriatic acid. I soaked a sponge and rubbed it on the stain on the wall and it came right off in seconds. Next, in a different area, I rubbed a chlorine puck on the stain, but that didn't make any difference. So I decided to leave the puck on the stain for a while. Well, I forgot to take it out a few minutes later and it sat overnight. When I remembered and took it out in the morning, the majority of the stain was still there, but a ring of staining was removed where the outside of the puck was touching the Diamond Brite plaster finish. Lastly, I just noticed these dark bumps appear here and there, but only on the stain ring area.

Chlorine Tab.jpg

Stain Bumps.jpg

So, sorry for the insanely long post, but any thoughts?
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
9,121
NY
Hey Sky !! Pool school has a section for you. :) TLDR : use a puck for organic stains and an AA/Vitimin C tab for metals.
 
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Texas Splash

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It does sounds as though you have some copper issues since Jack's worked and so did the muriatic acid. I wouldn't expect copper staining to be so uniform everywhere like it is, but perhaps there is something to the scale thought as well. Have you ever had the water tested for copper? Pool stores aren't necessarily anymore accurate with that as their other testing, but it might useful in your case.
 

Skyline

Active member
Jun 17, 2016
35
PA
Hey Sky !! Pool school has a section for you. :) TLDR : use a puck for organic stains and an AA/Vitimin C tab for metals.

Yes, I read just about every topic here. I'm not sure if you missed it because I know my post was long (but I wanted to try to provide as much info and background as I could) but neither Vitamin C nor chlorine pucks really made a difference. The chlorine puck had a slight affect after sitting on the stain for a day, but I'm not sure if the chlorine affected an organic stain or if it caused any scale to dissipate. Also, when I rigorously ground a chlorine puck on the stain and let it sit there for several minutes it had no affect.

I created this post to hopefully get some expert insight because I was not able to get satisfactory answers from any of the articles and what I've done so far.
 
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Texas Splash

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Understand, That explains why the Vitamin C (iron) and chlorine (organic) didn't have any effect. Acid on the other hand impacts two things - scale and copper.
 

Skyline

Active member
Jun 17, 2016
35
PA
It does sounds as though you have some copper issues since Jack's worked and so did the muriatic acid. I wouldn't expect copper staining to be so uniform everywhere like it is, but perhaps there is something to the scale thought as well. Have you ever had the water tested for copper? Pool stores aren't necessarily anymore accurate with that as their other testing, but it might useful in your case.

I haven't had my water tested for metals. Like you said, I'm not sure how accurate it would be and if it would provide relevant and reliable results to go off of.

I can't argue with you regarding copper being in the water and being the source of the staining because I really don't what what is causing it. It could be copper, but where did it come from? I didn't use any copper-based algecide ever. Also, why was I able to remove all the stains last year with no special chemicals. And once the stain was gone, assuming it was copper, why didn't it come back at all during the entire year, especially noting that I didn't use any sequestrant to keep the copper at bay? And like you said, why is and was the staining only in a ring where the water level was over the winter?

I see your direction with the stain ID testing and the muriatic acid, but wouldn't the results be essentially the same if it was just dirty organic scale? And if it were copper, would the test where I left the chlorine puck on the stain overnight that had a slight affect on it still do that to copper? Or just organic based staining?
 

Texas Splash

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Besides metal content we have to remember that the pH plays a major role. Over the winter your pH shoots-up and that will agitate metals for sure. But if that was the issue, I would expect to see copper staining in the entire pool. As for a source, copper is almost always from a manmade source. If not an algaecide, sometimes equipment or copper plumbing. But a chlorine tab won't do anything to copper, perhaps make it worse. You have a few twists and turns in yours that aren't cut & dry.
 

Skyline

Active member
Jun 17, 2016
35
PA
Besides metal content we have to remember that the pH plays a major role. Over the winter your pH shoots-up and that will agitate metals for sure. But if that was the issue, I would expect to see copper staining in the entire pool. As for a source, copper is almost always from a manmade source. If not an algaecide, sometimes equipment or copper plumbing. But a chlorine tab won't do anything to copper, perhaps make it worse. You have a few twists and turns in yours that aren't cut & dry.

Lol, I hear you about twists and turns and not being cut and dry! I wish it was, though.

Thanks for the feedback though. So if you had to tackle this, what would you do?
 

Texas Splash

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I might try to get a copper test just for additional confirmation. Even if it's not 100% accurate, just to see if I'm on the right track. Your Poolmath CH isn't high at all, so aside from an elevated winter pH, there's not much reason to expect scale.
 

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Skyline

Active member
Jun 17, 2016
35
PA
I might try to get a copper test just for additional confirmation. Even if it's not 100% accurate, just to see if I'm on the right track. Your Poolmath CH isn't high at all, so aside from an elevated winter pH, there's not much reason to expect scale.

I'll see what I can do about getting a copper test done.

I closed the pool last year with a CH of 420, and it was 300 when I opened this year. I don't know where it went. Well, I did have to add some water to bring it back up to the proper skimmer level. Maybe that's why it's different.

I expect scale the first opening last year following the new plaster, but i agee that I did not expect scale this year too. But I could definitely feel the scale on the surface when I opened this year compared to last year. You could even tell the noticeable difference between the plaster that was underwater versus plaster just below the tile line that was out of water.
 

Texas Splash

Mod Squad
TFP Expert
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Jun 22, 2014
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I closed the pool last year with a CH of 420, and it was 300 when I opened this year. I don't know where it went.
On the pool's surface. That could certainly explain the discoloration, why the number ddropped, and why acid worked on it coupled with your aggressive brushing,
 

Skyline

Active member
Jun 17, 2016
35
PA
Just checking to see in anyone else has any insight on what this staining might be.

Also, could I do a no-drain acid wash using muriatic acid to clear the staining? If so, how would I go about doing so?

Thanks
 

Funky145

Member
May 26, 2010
9
North Eastern, NJ
I had my pool resurfaced with Diamond Brite 5 years ago and I think it's the same color as yours. 2 years ago I opened my pool in late May to a green swamp. After slamming, I had the same green ring around the pool that you do, even the same width! I slammed the pool for a month straight using close to 100 gallons of liquid chlorine with very little change. However, by the end of the season and with regular maintenance, the stain had lightened considerably. Last year I opened the pool before the water turned green and noticed the faint ring still visible. By the time I closed it last year, the ring was virtually gone.

I don't know what the cause of the ring was, but time and proper balances seem to have cleared mine up.

I also have 1 of those brown dots / streaks, I think it's from lawn fertilizer.
 

Skyline

Active member
Jun 17, 2016
35
PA
I had my pool resurfaced with Diamond Brite 5 years ago and I think it's the same color as yours. 2 years ago I opened my pool in late May to a green swamp. After slamming, I had the same green ring around the pool that you do, even the same width! I slammed the pool for a month straight using close to 100 gallons of liquid chlorine with very little change. However, by the end of the season and with regular maintenance, the stain had lightened considerably. Last year I opened the pool before the water turned green and noticed the faint ring still visible. By the time I closed it last year, the ring was virtually gone.

I don't know what the cause of the ring was, but time and proper balances seem to have cleared mine up.

I also have 1 of those brown dots / streaks, I think it's from lawn fertilizer.
Thank you so much for your reply. I'm sorry to hear that you went through the same thing, but I'm glad to hear that someone else has also experienced this phenomenon.

My pool is Diamond Brite like yours; the color is Super Blue, one of the more popular offerings.

So my bug question is, what was it like this year when you opened up the pool? Did you do anything different closing it last year or opening it this year?

And by regular maintenance, do you mean just keeping all the chemical at their target levels and regular brushing, filter cleaning, etc?

Thanks again!
 

Funky145

Member
May 26, 2010
9
North Eastern, NJ
Thank you so much for your reply. I'm sorry to hear that you went through the same thing, but I'm glad to hear that someone else has also experienced this phenomenon.

My pool is Diamond Brite like yours; the color is Super Blue, one of the more popular offerings.

So my bug question is, what was it like this year when you opened up the pool? Did you do anything different closing it last year or opening it this year?

And by regular maintenance, do you mean just keeping all the chemical at their target levels and regular brushing, filter cleaning, etc?

Thanks again!
 

Funky145

Member
May 26, 2010
9
North Eastern, NJ
Thank you so much for your reply. I'm sorry to hear that you went through the same thing, but I'm glad to hear that someone else has also experienced this phenomenon.

My pool is Diamond Brite like yours; the color is Super Blue, one of the more popular offerings.

So my bug question is, what was it like this year when you opened up the pool? Did you do anything different closing it last year or opening it this year?

And by regular maintenance, do you mean just keeping all the chemical at their target levels and regular brushing, filter cleaning, etc?

Thanks again!

I closed the pool in early September and opened it late in May the following year. Much earlier and warmer than I would normally do for either, but vacation plans required it. I now close as late as possible and will start the pump going in early May while the water is still clear.
 

Skyline

Active member
Jun 17, 2016
35
PA
I closed the pool in early September and opened it late in May the following year. Much earlier and warmer than I would normally do for either, but vacation plans required it. I now close as late as possible and will start the pump going in early May while the water is still clear.
Okay I'll make sure I open next year as early as practicality possible. Thanks.

Did opening it early this year prevent the stains compared to previous years?