Dark spot on pebble finish - not sure what to do!

[akavlie]

I have a pool with a dark area in the center near the drain. It has a white pebble finish.
The dark spot appeared within a couple of months of installation of the pool. I have not been able to get rid of it by brushing.
The surface around that area also feels a lot more course than the rest of the pool.

I reported to the pool builder, and they recommended acid washing (for $500), and recommended doing this every 2 years.
From what I've read here and elsewhere, acid washing is probably not a good idea. In any event, this remedy doesn't make sense for something that showed up only a couple of months after installation.

Based on threads I've read on this forum (e.g. this one), it sounds like this is likely a problem with the pool builder's installation.
I'm just not sure how to convince them of this, or how to otherwise get it fixed.

 

[ajw22]

Welcome to TFP.

How old is the plaster?

Is this an area where you have been pouring in chemicals?

@onBalance any ideas what is going on here?

 

[onBalance]

That discoloration may not have been caused by poor plastering work, and may have been caused by some sort of chemical staining.

I suggest trying TFP's recommended method for stain testing or having a scuba diver use sandpaper to see if the stain can be removed by sanding.

 

[JamesW]

Do you have pictures of the pool when it was new?

What plaster did you get?

 

[Dirk]

I suggest trying TFP's recommended method for stain testing or having a scuba diver use sandpaper to see if the stain can be removed by sanding.

Worth repeating. If you take this back to the builder, I can virtually guarantee you he'll want to acid wash your pool: drain it and spray it down with muriatic acid or worse. This is their lazy, cheap first resort to "fix" this type of problem, even before they figure out what the problem is. That may or may not mitigate the stain, but it will for sure skin a layer of plaster off your pool, permanently. Acid washing doesn't magically attack stains and leave "all the good stuff" alone. No, it removes a layer of plaster and takes the stain with it. You'll have less pool, and less plaster life, and the builder will get off cheap. Best case, it'll look some amount better but you won't feel the full effect of the acid wash until many years from now, when you're out of warranty, or your builder is long gone, and your plaster fails prematurely. Worst case, the acid wash will actually make it look worse and/or destroy some or all of your plaster (ask me how I know)!

As onBalance suggests, there are non-acid solutions to test for what the stain is first, and mechanical abrasion solutions that can be carefully applied to just a contained area to lessen it. But don't let them acid wash your pool to fix this.

 

[Dirk]

To be clear, I wasn't suggesting that you not take this issue to the installer, especially if you are still in your finish's warranty period. To have them fix this, (or to try and sue them for damages if they won't) you pretty much have to allow them the first crack at it. That's how warranties and lawsuits generally work. If you try to fix it yourself, or hire another to try, that will very likely void your warranty. And without ever notifying them about the problem, greatly reduce or eliminate any chance to make a claim (or sue for a judgement) against the original installer.

So you can contact them about it (in writing) and see what they say. If (when!) they come back with "We'll acid wash it," then you'll have to decide what is best for you. Or they may suggest some other fix. At that point, you might pause the process, come on back here with their plan, and ask about it here, before you decide.

 

[akavlie]

Welcome to TFP.

How old is the plaster?

Is this an area where you have been pouring in chemicals?

@onBalance any ideas what is going on here?

It's 2 years old.
I have not been pouring chemicals in over this spot.

 

[akavlie]

Do you have pictures of the pool when it was new?

What plaster did you get?

Not anything that clearly shows the pool floor.
The product is Pebble Radiance.

 

[akavlie]

Worth repeating. If you take this back to the builder, I can virtually guarantee you he'll want to acid wash your pool: drain it and spray it down with muriatic acid or worse. This is their lazy, cheap first resort to "fix" this type of problem, even before they figure out what the problem is. That may or may not mitigate the stain, but it will for sure skin a layer of plaster off your pool, permanently. Acid washing doesn't magically attack stains and leave "all the good stuff" alone. No, it removes a layer of plaster and takes the stain with it. You'll have less pool, and less plaster life, and the builder will get off cheap. Best case, it'll look some amount better but you won't feel the full effect of the acid wash until many years from now, when you're out of warranty, or your builder is long gone, and your plaster fails prematurely. Worst case, the acid wash will actually make it look worse and/or destroy some or all of your plaster (ask me how I know)!

As onBalance suggests, there are non-acid solutions to test for what the stain is first, and mechanical abrasion solutions that can be carefully applied to just a contained area to lessen it. But don't let them acid wash your pool to fix this.

I reported the issue to the builder before this thread, and they did indeed recommend acid washing. I talked with a pool cleaner they work with, and he recommended the same thing.

I tried some stain testing a while ago. I think I just did the organic stain test (putting a chlorine puck on the stain for a while) and that did nothing.
I have not tried the iron or copper tests.

 

[Dirk]

Here's something to check that is 100% non-invasive. Have you viewed the area up close with a dive mask on? And/or do you have an underwater camera? Look if this might be a finish application issue. Do you see areas that look like too much of the pebbles are revealed, or not enough, and they're covered with plaster? This is a long shot, because this sort of thing would usually be visible right off, not develop later. But it's worth ruling out.

PS. Don't breath-hold dive by yourself. Have someone standing by that could render medical assistance (CPR) just in case. Another long shot, but shallow-water blackout (however rare) is a thing, and if you're alone, not a good thing!

Non-invasive #2: is the finish under warranty? And is the warranty covered by a major pebble-finish supplier? Like PebbleTec or similar? Do you have it in writing? Mine was for five years. If you don't like the answers/solutions offered by the builder or installer, the material manufacturer can sometimes be coerced into sending a rep to your location for a warranty review. Typically, name-brand finish installers are "certified" by the material manufacturer, and in some cases the manufacturer will cover his work. This can sometimes lend itself to two negative possibilities: one, the installer might not want to involve the manufacturer, because he wouldn't want to jeopardize his certification, and two, the manufacturer might side with the installer, because they don't want to lose the installer from their "stable" of installers. It can be a one- or two-way conflict of interest! But if both entities are on the up-and-up, involving the manufacturer might get you a solution that the installer or builder would not be inclined to offer on their own. It might only cost you an email or a phone call.

If the builder or installer refuses to contact the manufacturer on your behalf, we've seen people go around them and contact the manufacturer directly, so that's a last ditch resort, too.

I got some other moves to try (like if all three entities insist on acid washing), but these are the first steps, before things get ugly. Just in case, be sure you're communicating in writing. If the situation doesn't allow that exclusively, be sure you have a witness attending any on-site verbal communications, and follow those up with an email or letter, just a "casual" recap: "We met on xxxx, Yyyy and Zzzz were present. Yyyy said blah, Zzzz said blah, blah. They recommended blah, blah, blah." etc. This accomplishes two things: it captures what was said in writing (so no he-said-they-said bs), and it sends a not-too-subtle message that you mean business. They'll get the hint. Now is not the time to threaten a lawsuit over this, but preparing for one can't hurt. Best case scenario is the builder stepping up and fixing the problem (without costing you years of plaster life). So you want to preserve that possibility by keeping the conversations amicable. But if you think you definitely cannot live with the stain, and would do whatever it takes to get it fixed, then a little "note taking" now will go a long way if things go south.

 

[akavlie]

Here's something to check that is 100% non-invasive. Have you viewed the area up close with a dive mask on? And/or do you have an underwater camera? Look if this might be a finish application issue. Do you see areas that look like too much of the pebbles are revealed, or not enough, and they're covered with plaster? This is a long shot, because this sort of thing would usually be visible right off, not develop later. But it's worth ruling out.

PS. Don't breath-hold dive by yourself. Have someone standing by that could render medical assistance (CPR) just in case. Another long shot, but shallow-water blackout (however rare) is a thing, and if you're alone, not a good thing!

Non-invasive #2: is the finish under warranty? And is the warranty covered by a major pebble-finish supplier? Like PebbleTec or similar? Do you have it in writing? Mine was for five years. If you don't like the answers/solutions offered by the builder or installer, the material manufacturer can sometimes be coerced into sending a rep to your location for a warranty review. Typically, name-brand finish installers are "certified" by the material manufacturer, and in some cases the manufacturer will cover his work. This can sometimes lend itself to two negative possibilities: one, the installer might not want to involve the manufacturer, because he wouldn't want to jeopardize his certification, and two, the manufacturer might side with the installer, because they don't want to lose the installer from their "stable" of installers. It can be a one- or two-way conflict of interest! But if both entities are on the up-and-up, involving the manufacturer might get you a solution that the installer or builder would not be inclined to offer on their own. It might only cost you an email or a phone call.

If the builder or installer refuses to contact the manufacturer on your behalf, we've seen people go around them and contact the manufacturer directly, so that's a last ditch resort, too.

I got some other moves to try (like if all three entities insist on acid washing), but these are the first steps, before things get ugly. Just in case, be sure you're communicating in writing. If the situation doesn't allow that exclusively, be sure you have a witness attending any on-site verbal communications, and follow those up with an email or letter, just a "casual" recap: "We met on xxxx, Yyyy and Zzzz were present. Yyyy said blah, Zzzz said blah, blah. They recommended blah, blah, blah." etc. This accomplishes two things: it captures what was said in writing (so no he-said-they-said bs), and it sends a not-too-subtle message that you mean business. They'll get the hint. Now is not the time to threaten a lawsuit over this, but preparing for one can't hurt. Best case scenario is the builder stepping up and fixing the problem (without costing you years of plaster life). So you want to preserve that possibility by keeping the conversations amicable. But if you think you definitely cannot live with the stain, and would do whatever it takes to get it fixed, then a little "note taking" now will go a long way if things go south.

Thanks for the ideas, appreciate it.

I don't have a dive mask or an underwater camera.
I'm not sure about a warranty on the pebble finish, but I may contact them to ask about it.