Having trouble with brown spots

[chrisg7]

Just recently I started to notice quite a few brown spots in my pool. The water has been perfectly blue and clear all winter and they just started coming up this Spring. I manage the chlorine and other chemicals on a regular basis and couldn’t figure out what was wrong.

I started a SLAM on Monday just to be safe, even though the water looks great. I passed the overnight chlorine test last night (although I hadn’t passed the night before) and I’ve never really had any combined chlorine on my test readings. The only thing I have are these brown spots. And there are quite a few of them.

Last year I had something similar and they looked like cobalt stains. All radiating out from one spot. As a result, I had a full re-glaze done on my fiberglass pool in August.

But now the stains are back.

Should I keep SLAMing for a week or more just to see if it does anything? I can’t tell that the SLAM is lightening up the spots at all.

I feel like the best way to describe the spots are brown spots radiating out from a central point.

I’ll attach a few pictures.

Thanks for any help you can give!

 

[chrisg7]

@ajw22 @Bperry I appreciate you helping me on a previous post and thought you might have some insight here as well.

 

[ajw22]

They look like metal stains.

Have you tried rubbing a paste of Vitamin C in a sock on the areas?

 

[Bperry]

@ajw22 @Bperry I appreciate you helping me on a previous post and thought you might have some insight here as well.

My only guess would be some kind of stain from acorns, seeds, etc. See if you can scrape some off. Might try and rub some vitamin C tablets on it to see if its iron.

 

[chrisg7]

@Bperry @ajw22 I rubbed some Vitamin C on the spots that it seemed to get rid of most of it. There’s still a black pimple at the center of each of them that I can’t easily scrape off with my finger. But the Vitamin C definitely removed most of the stain. Any thoughts on the black pimples and does this mean I need to do a full Vitamin C treatment on my pool?

Thanks!

 

[ajw22]

@Bperry @ajw22 I rubbed some Vitamin C on the spots that it seemed to get rid of most of it. There’s still a black pimple at the center of each of them that I can’t easily scrape off with my finger. But the Vitamin C definitely removed most of the stain. Any thoughts on the black pimples and does this mean I need to do a full Vitamin C treatment on my pool?

Thanks!

No, a full AA treatment in your pool will not do anything different then spot treatment of the stains.

I wonder if they are from rusting rebar leaching to the surface of the plaster.

How old is your pool?

 

[chrisg7]

No, a full AA treatment in your pool will not do anything different then spot treatment of the stains.

I wonder if they are from rusting rebar leaching to the surface of the plaster.

How old is your pool?

About 44 years old. Just recently did a new gel coat and repaired the fiberglass. If the Vitamin C tablets are working for spot treatment, shouldn’t I go ahead and treat the whole pool? @ajw22

 

[ajw22]

If the Vitamin C tablets are working for spot treatment, shouldn’t I go ahead and treat the whole pool? @ajw22

Depends how widespread the staining is.

Takes more work to do the whole pool and it upsets your water chemistry.

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

 

[chrisg7]

Depends how widespread the staining is.

Takes more work to do the whole pool and it upsets your water chemistry.

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

Here’s another interesting observation.

When I take the Vitamin C tablets and rub them down the wall of the pool, those areas become so much whiter than the areas around it. Even when there’s not a stain there. I can tell the entire walls are not totally white, but once I use the Vitamin C tablet, it turns the walls white anywhere I rub it. Does that tell us anything? @ajw22

 

[ajw22]

Sounds like your entire pool has iron staining and those spots were just the tip of the iceberg.

I would figure out where you got iron in the water from and how to get clean water.

Iron Fill Water Filter - Further Reading

www.troublefreepool.com

 

[chrisg7]

Sounds like your entire pool has iron staining and those spots were just the tip of the iceberg.

I would figure out where you got iron in the water from and how to get clean water.

Iron Fill Water Filter - Further Reading

www.troublefreepool.com

Yeah, I’m totally confused. I live in DFW and I’m not aware of iron in the water. I filled up the pool with city water. Do you think I need to do an AA treatment? Or just wait until the end of the season? I just feel like the number of stains is accumulating. It started with a few and now I’d say there are at least 15 and the walls aren’t discolored in a major way, but definitely get whiter when I run the Vitamin C tablets on them.

 

[ajw22]

Yeah, I’m totally confused. I live in DFW and I’m not aware of iron in the water. I filled up the pool with city water. Do you think I need to do an AA treatment? Or just wait until the end of the season? I just feel like the number of stains is accumulating. It started with a few and now I’d say there are at least 15 and the walls aren’t discolored in a major way, but definitely get whiter when I run the Vitamin C tablets on them.

The problem is cosmetic. You can decide if, when, and how you want to treat it.

Somehow you got iron in your water.

 

[chrisg7]

The brown/black spots have continued to multiply. I’m concerned that even if an AA treatment works, I don’t know where the iron is coming from. Could it be the age of the pool being that it’s over 40 years old? Could iron be making its way through the Fiberglass even though I did a new gel coat and fiberglass repair last year? Could it be iron piping that’s old which the water runs through? @ajw22 @Bperry

 

[chrisg7]

@Texas Splash @JoyfulNoise :: Any thoughts?

 

[Texas Splash]

We are a bit in uncharted territory. If this was a new shell, I'd say no way, it's the local water or something local got blown into the pool. But with a FG shell that old, I suspect the construction of the shell included plaster and who knows what else for reinforcement before the fiberglass coatings were applied.

Do you have any detailed information about the most recent gelcoat application done last year? Any pics or info from the contractor that might point to issues from the legacy surface?

 

[JoyfulNoise]

You can try Jack’s Magic #1 Iron, Cobalt, Spot Etching stuff to see if that works.

As others have suggested, the age of the pool surface is likely the issue. Doing gel coats is like doing skim coats on a plaster pool, it’s just a band-aid that covers over a compromised surface. It’s probably time to start saving up for a new pool shell.

Also, you mentioned cast iron pipes … do you know for sure that the pipes are cast iron? If they are, that’s the likeliest source of your staining problems. Buried iron pipes eventually corrode and decay. Once the corrosion starts, there’s no stopping it. Modern pool construction no longer uses cast iron or copper pipes at all anymore for both cost and lifetime issues.

 

[chrisg7]

We are a bit in uncharted territory. If this was a new shell, I'd say no way, it's the local water or something local got blown into the pool. But with a FG shell that old, I suspect the construction of the shell included plaster and who knows what else for reinforcement before the fiberglass coatings were applied.

Do you have any detailed information about the most recent gelcoat application done last year? Any pics or info from the contractor that might point to issues from the legacy surface?

I’ll attach some pictures of the pool from the re-gel coat last year. These pics were taken right after they drained it. They then sanded it down. Repaired the fiberglass that needed it. Then applied a new gel coat. Let me know if this tells you anything. The reason I had it re-gel coated is because these same spots appeared last year but they were even deeper and you could see some of the green shell, which told the contractor we needed some fiberglass repair before the re-gel.
@Texas Splash
@JoyfulNoise

 

[chrisg7]

You can try Jack’s Magic #1 Iron, Cobalt, Spot Etching stuff to see if that works.

As others have suggested, the age of the pool surface is likely the issue. Doing gel coats is like doing skim coats on a plaster pool, it’s just a band-aid that covers over a compromised surface. It’s probably time to start saving up for a new pool shell.

Also, you mentioned cast iron pipes … do you know for sure that the pipes are cast iron? If they are, that’s the likeliest source of your staining problems. Buried iron pipes eventually corrode and decay. Once the corrosion starts, there’s no stopping it. Modern pool construction no longer uses cast iron or copper pipes at all anymore for both cost and lifetime issues.

I attached some pics above of the pool surface after draining last year but prior to re-gel cost.

No, I don’t know for sure that the piping is cast iron. I know the plumbing under our house for bathrooms, etc is cast iron, so we figured this could be as well. Is there an easy way to find out for sure if the pipes to the pool are cast iron?

Instead of Jack’s Magic #1, I bought 3lbs of Ascorbic Acid as recommended in the AA article. Once the season was over, I was going to experiment with an AA treatment using the Ascorbic Acid and then I got Jack’s Magic Pink Stuff for the sequencing agent. Should I use Jack Magic #1 instead or try the AA treatment first?

Any other thoughts or suggestions?

@JoyfulNoise
@Texas Splash

 

[Texas Splash]

Thanks for the pics. Unfortunately, I can't really see anything to answer the main question of the reoccurring stains. I do see what appear to be a few tannin stains (brown and look like comets) on the floor, but I suspect that's different than what you are trying to resolve.

 

[chrisg7]

Thanks for the pics. Unfortunately, I can't really see anything to answer the main question of the reoccurring stains. I do see what appear to be a few tannin stains (brown and look like comets) on the floor, but I suspect that's different than what you are trying to resolve.

Those “tannin” stains are what we were trying to correct with the gel coat. And that’s what I’m dealing with now as well. They are little black/brown dots in the middle that look like comets as they spread out from the middle. We’ve got them all over the pool. They have seemed to respond a little to rubbing Vitamin C on them. That’s why I was planning to do an AA treatment at some point. @Texas Splash