Scale? on new StoneScape Re-Surface

[bagsofcole]

Hi All,

We had our pool resurfaced last June and after fighting leaks, blocks, and COVID, we're swimming again. However our surface has been changing colors since September and I'm not getting anywhere with the re-surface contractor. He seems to think it's scale. To me it appears the outer layer of color is coming off... Thoughts?

 

[mknauss]

Doesn't look like scale to me either. Do you keep records of water chemistry? Do you test your own water chemistry?
@onBalance will likely be able to pinpoint the issue.

 

[bagsofcole]

Doesn't look like scale to me either. Do you keep records of water chemistry? Do you test your own water chemistry?
@onBalance will likely be able to pinpoint the issue.

Yes, I've been meticulously, obsessively tracking and balancing the water since the resurface with the Pool Math app and test kit I purchased via recommendation from this forum, and a monthly visit to the local pool store to keep the surface "warranty" valid. We did have a leak from June to November when the installer finally drained the pool and re-concreted the main drain, so keeping the chemistry balanced then was tricky since we were constantly adding water. I add 8oz a week of Jack's Magenta per week as suggested by the installer. Here are my latest readings, I believe I'm fighting too much stabilizer the installer added since the leak repair and refill:

FC 2.5
CC 0.0
pH 7.5
TA 70
CH 450
CYA 65
CSI -.03

 

[mknauss]

Great. Your FC is too low, but that is not causing the plaster issues.

Let's wait on advice from onBalance.

 

[bagsofcole]

Great. Your FC is too low, but that is not causing the plaster issues.

Let's wait on advice from onBalance.

Thanks and yes I agree, my CYA has been steadily dropping from 90 since we refilled in December so I am adding more chlorine. After this reading the Pool Math app suggested 74 oz of 10% bleach and I followed that direction.

 

[onBalance]

No, that is not a calcium scaling condition. If it were, the pebbles would also have white scale deposited on them and be more uniform throughout the pool, and that does not appear to be the case.

It appears that this pool finish is an exposed pebble finish, and not a smooth quartz finish. It also appears that a blue color pigment was used to color the cement in the plaster. The contractor may have performed a power washing (and perhaps acid treatment) to remove some cement and exposed the pebbles. If so, then one possibility is that the "water washing" (and perhaps acid washing) of the surface was not done uniformly and consistently throughout. The areas that are lighter in color probably were "over-treated" and became more porous. If so, then the color could more easily be dissolved out of those porous areas and lighten in color over time.

Another possibility is that the blue pigment used (and added) in the plaster mix is being bleached by chlorine and sunlight. There are cheaper brands of pigments (often organic) that slowly lose their color in chlorinated water. The more expensive pigment types do not. This second possibility, however, is not following typical and similar traits of colors bleaching out. So, you might want to rule that situation out.

 

[bagsofcole]

No, that is not a calcium scaling condition. If it were, the pebbles would also have white scale deposited on them and be more uniform throughout the pool, and that does not appear to be the case.

It appears that this pool finish is an exposed pebble finish, and not a smooth quartz finish. It also appears that a blue color pigment was used to color the cement in the plaster. The contractor may have performed a power washing (and perhaps acid treatment) to remove some cement and exposed the pebbles. If so, then one possibility is that the "water washing" (and perhaps acid washing) of the surface was not done uniformly and consistently throughout. The areas that are lighter in color probably were "over-treated" and became more porous. If so, then the color could more easily be dissolved out of those porous areas and lighten in color over time.

Another possibility is that the blue pigment used (and added) in the plaster mix is being bleached by chlorine and sunlight. There are cheaper brands of pigments (often organic) that slowly lose their color in chlorinated water. The more expensive pigment types do not. This second possibility, however, is not following typical and similar traits of colors bleaching out. So, you might want to rule that situation out.

That sounds exactly like the situation. The surface started as mostly uniform darker blue and has (not so)slowly started to fade. I suppose it will all eventually fade to the lighter blue? I guess as long as it becomes uniform I'm not so concerned, but it looks bad when it's spotty as it is. Obviously we haven't had the best of luck with our pool rehab and did go with one of the cheaper contractors... I guess sometimes you do get what you pay for!

The pool sits on the north side of the house and is shaded by the house and screened enclosure. We read the Stonescape warranty and it doesn't seem to cover aesthetics, and I'm not sure I want that contractor touching the pool anymore, I finally got everything else working well and don't want to risk another issue. Thanks onBalance, you've given me a piece of mind and confirmation that I don't need to de-scale, if that is even a thing.

 

[bagsofcole]

So we called the manufacturer and they are going to send out a rep to show us how it's scale and hopefully fix it with an acid bath or something.

 

[onBalance]

Sorry to be the bearer of negative info, but here is what an acid bath can do. Acid baths etches and removes plaster material that has lost some pigment color. That in turn, exposes plaster material underneath that still has the full darker color in tact. And then because the whitish plaster (color loss material) has been removed, that darker color result is cited and used to conveniently claim that the whitish color was calcium scaling. But what will happen in the near future? The now etched plaster surface (the colored cement portion surrounding the pebbles) is rough and also somewhat porous and probably will easily lose its' color and turn whitish again. At that point, the contractor may claim that it is scale again and not do anything more for you, or at least until your pool is ready for another re-plaster sooner than normal due to a heavy acid wash.

I would ask the rep to explain how water imbalance could cause scale (white deposit) very randomly, in small spots, in large areas, AND how the color can change horizontally and so distinctly a foot or two down and along a wall as seen in your photos? Would not water imbalance cause calcium scale everywhere and uniformly? It does in scaled pools I have seen.

 

[bagsofcole]

Thanks for the advice, makes sense to me. Combining all of the other problems we’ve had with this job it figures we’d have this issue as well. I appreciate the wisdom and hopefully will be able to use it to make the situation right.

 

[onBalance]

Here is the article that explains this issue in detail. Perhaps give it to those that will be looking at your pool.

Why Colored Plaster Turns White

Plaster colors can fade or turn whitish for a handful of preventable reasons. First off, scale can be deposited onto pigmented plaster surfaces by out-of-balance pool water. As is widely known, calcium scale makes the surface rough and turns it white, and acid washing is often the remedy...

www.troublefreepool.com