Diagnostic help please - scale? calcium?

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shacke

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Jul 5, 2010
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Philadelphia
I thought I had posted on this before but I guess I never did. I have always atributed this issue to calcium and I scrape it off but I am not sure anymore. Maybe someone here can help me eradicate it.

It's hard to get a picture but little white splotches appear on the plaster. This happens a lot over the winter when the pool is closed but they do also occur during the season. In the picture you can see the raised spots - all under the tile level - and some of them have a teardrop appearance or like melting wax. It is gritty and can be removed with a scrungie although I cant get them all and they are everywhere in the pool.

[attachment=0:19qzrxxc]photo (20).JPG[/attachment:19qzrxxc]

My chemistry is pretty much humming at this point but the only thing I grapple with in terms of fluctuation is the pH rising because of my SWG. I typically add MA weekly no matter what so the pH does swing rapidly over the week from maybe 7.2 to as high as 7.8-8.0 (occasionally)

Here are the latest numbers which have been pretty typical (other than the temp which is usually higher like 83 but we were away and the heat was off).

temp 76
pH 7.6
CH 250
CYA 70
FC 14.0
TA 100
CSI -0.15

Thanks a lot. :-D
 

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Pretty good bet it is calcium scale.....and another pretty good bet that they may have been produced by bouts of high pH in the past.

If it was my pool, I would take the pH down to 7.0 and keep it there very diligently for at least two weeks to see if they loosen or perhaps go away.

I would also suggest reducing TA down to 60 or thereabouts.....that may reduce the speed with which the pH rises. Learn how to reduce TA up in Pool School.
 
Is this pool a re-plaster over old plaster? Is there craze cracking (fine line cracking) evident? If so, do you see the crack lines running underneath the white calcium nodules?
From the picture, this dark colored plaster job does not look like it has been painted over.
 
When scaling occurs due to a high pH, it causes a uniform scaling all over the pool, much like a sandpaper effect. Your pool appears to have random raised white "calcium nodules" which are not caused by high pH or imbalanced water. Calcium nodules are caused by cracking or bond failure of the plaster from the substrate. Have you drained the pool recently?

Your black colored plaster has also loss some color (darkness) and has turn somewhat lighter or whiter in color and now is very blotchy. That is from the loss of the black pigment color that was added to original white cement to make it "black." That sometimes happens after a few years time has past.
 
It has been a few years since it was painted, before I moved in in 2008 actually. The darker color has become more variegated over time.

There is no crazing on the walls whatsoever. The pool has not been drained since I owned it - other than for winterizing (below the returns). The spots are all over - even at the bottom.

Once the spots are rubbed off, the underlying plaster wall appears just fine.
 
When sanding off calcium nodules, the plaster underneath will be smooth and look okay from a distance. But with the help of magnifying glass, you may see a small white pinhole.
 
When removing the white calcium nodules, they sometimes will return several times before they stop. Try not to have to drain the pool, as it will just make it worse. So yes, since the pool is several years old, nothing can be done until it needs replastering.
 
Now that I think of this, I wonder if the dust on the bottom of the pool I see is related to the plaster "going". I thought it was DE but it's not. It's been there all summer and recollects.

I was told by prior owner that I shouldn't fill the pool with softened water because it would hurt the paint and plaster but learned in here that that is untrue.

I hope so. Is this process part of the normal aging for the paint and plaster? I was told by the pool company that the heterogeneity and lightening of the paint color is.

I dont want to redo it. I can only imagine the cost so anything I can do to stall a redo I will do!
 

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shacke said:
I was told by prior owner that I shouldn't fill the pool with softened water because it would hurt the paint and plaster but learned in here that that is untrue.
Click to expand...
They were probably assuming that you would keep the water soft after filling the pool with such water, but that's not what you did. From your Calcium Hardness (CH) it's apparent that you added calcium chloride to the pool to increase the hardness, which is what you are supposed to do to get to proper balance for a plaster pool.

What did the prior owner expect you to do? Have some sort of separate mixing tank making the fill water harder prior to adding it to the pool? Or was he referring to water used for auto-fill or make-up water for evaporation? If the latter, then the prior owner was wrong.
 
Add this to the misinformation my pool folks have levied against them over the years.

They were told to use soft water. Our house has a whole house softener with a bypass and they used to bypass the softener in the summer months. I do not.

Still, this thread has been helpful to me. The plaster was resurfaced with dyed plaster about 10 years ago. I anticipate that I will sell my house in 12-15 years. Given the potential cost, I would like to redo this once before then and also not hand off a pool to the next person who must immediately do such a project.

I spoke to the restoration folks today who told me I could go on the least expensive side and give it a shot of epoxy, after that there are several plaster replacement interval steps of increasing aesthetics and greater durability, ending with the most costly - pebble-tec.

I was told the pebble-tec would last 15 years. Is this an exaggeration? If not, I might be tempted to enjoy it longer by doing it sooner, rather than waiting.
 
Went into the pool today and scraped away a lot of the 'candle wax'. The problem is definitely worse this year and now I can see that the underlying plaster is cracked/worn.

I don't think I asked this above but is that a typically finding with plaster that is wearing down or is it also realted to the quality of the install?
 
No, it is not typical with plaster wearing down. It is hard to tell from the picture, but in my opinion, it probably has something to do with bonding the new plaster to the old plaster, or maybe from shrinkage cracks caused by a overly high water to cement ratio, a high calcium chloride content, etc., during the original plastering job. Achieving a good "bond" is more difficult the second time around.
 
Thanks for your continued help here. The picture in the OP shows the nodules but there are many divots, pits and diminuitive rents in the plaster.

I am surprised by the acceleration of the process over the last 3 years.

Hopefully, in up front discussions with the restoration folks, I can avoid a recurrence.
 
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