plaster discoloration

dutchessmomApril 30, 2008

Our pool was completed in Nov., a month or so later we noticed a light grey patch in the deep end, kinda looked like a shadow. The shadowing has spread thoughtout the whold pool, including on the walls, on the walls it almost looks like it ran down them. There is very little "bright white" left, it all looks like a light grey. You can't really see it when it is sunny, but when it is cloudy it really shows up.

We just did a stain remover treatment and metal out. It has been several hours with no improvement. We were really hoping for an easy fix.

We have a salt water system, PH running between 7.8 and 8, total alk. 100-120. our salt is running 3200ppm.

Please help, it seems that all of the pool supply peaple have NO CLUE...

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The key is to know what it is. Is there anything you or any other family remember can remember to account for it?

    Bookmark   April 30, 2008 at 10:21PM
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No not at all. This actually started showing up before we were even able to swim.

    Bookmark   May 1, 2008 at 10:50AM
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Any pictures? Have you asked the person that did your plaster about it? Rereading it sounds like its "most" of the pool at this point not an isolated spot...right?

    Bookmark   May 1, 2008 at 12:04PM
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We did ask the pool builder about it and initially he told us that it could be from adding the salt and letting it sit in one place, however... he is the one who put in the salt and with it being on the walls as well leads us to believe it is not the salt.
Yes it is pretty much over the whole pool, it started as 2 spots on the bottom in the deep end, one the size of a dinner plate and the other about the size of a standard pillow. Those 2 spots are now darker but the rest of the pool seems to be a lighter version of it. There are a few places that are still bright white but not many.
I currently do not have a picture showing this but I will try to get one tonight.

    Bookmark   May 1, 2008 at 12:57PM
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Hard to tell without seeing pics, but it may be plaster corrosion. Have you been testing your CH (calcium hardness)? CH is supposed to be kept between 200 and 400 with gunite pools. If CH is really low then the water dissolves calcium out of everything it can including the plaster.

    Bookmark   May 1, 2008 at 1:59PM
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when testing with the strips and at the pool supply place the hardness is reading around 250. When they say "hardness is good" does that mean "calcium hardness"?

    Bookmark   May 1, 2008 at 2:08PM
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There are two different tests, one for Calcium hardness and another for overall hardiness. You can have an overall hardiness of 250 but calcium hardness of only 100 for example.

It sounds to me like your pool company is gearing towards giving you the old, "its because you wanted to use salt, which we told you not to."

Anything particular about the location like a side that gets more sun, less sun, under a tree?

    Bookmark   May 1, 2008 at 2:43PM
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Oh ok, I will have to run a sample to the pool place and have them test the CH just to be sure.
As far as location, we cut down all trees in the area of the pool, the pool runs N to S, pool is in the shade in the early AM from the house, and starts to shade around 4pm from the waterfall and rock wall. It is all pretty uniformed.

    Bookmark   May 1, 2008 at 3:12PM
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Sounds like you might be a candidate for a no drain acid wash.

    Bookmark   May 1, 2008 at 3:17PM
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Real easy test you can do to see if it is a stain on the surface of the plaster,(your responsibility), or whether it is in the plaster,(plasterers responsibility). Take a piece of #60 or #80 WET and dry sandpaper and sand one of the spots in a small area to see if the discoloration disapperars. You can also carefully scratch through the plaster finish with a small screwdriver or knife to see if the plaster underneath is white. If it does not turn white when you scrape off the finish than the discoloration is all the way through the plaster and should be warranteed. If it does turn white it is a surface stain and is your responsibily. If the stain is all the way through the plaster than I am going to suspect what we call modeling or hydration which is moisture behind the plaster that cannot escape. This problem was real bad back in the 90's but I have not seen any in awhile. Can usually be cured by draining and giving a light acid rinse to the finish and letting set dry a couple of days. Have also used a torch to speed up the process on ones in the past.

Good luck

    Bookmark   May 1, 2008 at 6:08PM
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The first picture shows one of the large darker spots, however the rest of the bottom around this spot is a lighter shade of grey. The second one shows and area at the bottom of a wall that has the grey with some white still left. This is all over the pool. I hope these pics help.

    Bookmark   May 1, 2008 at 10:11PM
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I don't see the images...what are the hyperlinks suppose to be? Preview the pics in a browser by themselves and cut the address out for posting.

    Bookmark   May 1, 2008 at 10:28PM
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I get this.
The requested URL was not found



    Bookmark   May 1, 2008 at 10:44PM
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Can you try again, I changed the settings on the pictures so that others can view them.

    Bookmark   May 2, 2008 at 7:54AM
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I can see the pics just fine, but it is really hard to tell if it's staining or etching. You might try the test "dapooltec" suggested next.

    Bookmark   May 2, 2008 at 11:28AM
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It doesn't look like a stain to me. Its too broken up and irregular. It looks like a more serious problem. Recheck the water chemistry and make sure that is not the problem. Correct it if its wrong. Do the scratch test...that sounds very logical to determine how deep it is. If its NOT deep, I would suggest an in pool acid wash....just basically dump enough acid in the pool to get the PH below 6 and don't swim in it during this time. Let it sit for 3 or 4 days and try and brush it off....the acid wash and brushing may force it back or may make it so its not so noticeable. If its more than a mm deep, then you got problems with your plaster job and you will be for complaining back to the plaster company and probably a fight on your hands. Good luck.

    Bookmark   May 2, 2008 at 1:07PM
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Thank you for all of your thoughts. I bought a stain identification kit last night. I will try that this evening and see what is going on, as well as do what dapooltec suggested. I am soooooooo realllllllly hoping that I can fix this easy. I just want to enjoy my pool, not have to fight.

    Bookmark   May 2, 2008 at 3:24PM
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Dutchess-Did you ever resolve your problem? If so, please let me know how. I have similar issues. Thanks.

    Bookmark   March 18, 2009 at 1:34PM
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You have what is called calcium cylicate hydration 'The formation of glass', I would bet that you have low calcium fill water and the ponding water never received calcium chloride at startup as reccomended by the national plaster council in there technical section. Since they plaster using calcium to speed up the set rate the higher calcium concentrated areas are the dark areas in your pool. The plaster has a inability to hydrate while the plaster is maturating calcium to the ponding low calcuim tap water. The difference between the tap ch ppm and approx 220ppm was extracted from the plaster. If you did add calcium at what rate did you add it and what purity level %77 or %94? And no that's not under any warranty since warranties only extend to material and workmanship. If you have a low carbon alkalinity this would be called the 'deadly Duo'. If you have severe dark spots they may need a carbon heat treatment. for light discoloration throughout a 0 alk procedure will hydrate the effected areas in 7 to 14 days depending on water temp. Ie. moisture is trapped in the plaster.

Here is a link that might be useful: austin pro leak

    Bookmark   July 24, 2010 at 10:34AM
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