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Thread: Help! - New Plaster Blemish

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    Help! - New Plaster Blemish

    Our brand new pool replaster project was completed in late October and after "Start-up" process, there are blemishes all over the pool. The pool plaster company does not do start-ups [I was informed of this as the pool was filling...] and upon inspection today, acknowledged the blemishes then blamed it on the pool start-up guy. The start-up guy kept a log [for just this reason] yet the plasterer guy was not interested in looking at it. Nonetheless the plasterer guy has offered to acid wash the pool. Is this a good idea? How many acid washes does a plaster pool have before needing replaster?

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    Join Date
    Jul 2011
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    Arizona & California
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    Re: Help! - New Plaster Blemish

    The people on this forum would want to know what the chemical readings (chlorine, pH, TA, and CH) of the pool water now, and of the tap water used to fill the pool.
    Also, is this a typical white plaster, colored, or a quartz finish? What color are the blemishes? Are they rough to the touch? The size of the blemishes? Any particular area of the pool affected more than other areas?
    I think you should know what caused the problem before an acid wash is performed. Acid washes always age a plaster job and can only withstand a few well enough depending on how strong the acid solution is and how long the acid sits on the plaster.
    And best of all, can you send some pictures?

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    Re: Help! - New Plaster Blemish

    Looks like I need to gather more info, but here's what little I have:
    Chlorine - 0 from the start and still 0, though we have a floater with tabs going
    pH - 7.6 at fill, down to 7.5 for 2-weks then now 7.8 after some heavy rain
    TA - this is confusing. day 1-Started at 800, day 2 then to 900 added some acid day 3 down to 800, day 4 to now (~2 weeks later) pool guy entered "10.0" and "11.0" under the column for TA readings.
    That's all, I will get a full test tomorrow.
    Plain, basic white plaster. Blemishes are grey and all over, deep end, shallow end, sunny side walls, shady side walls. All over. Nylon brush does nothing. Feels just the same as the rest of the plaster. No pics, but will try to upload later.
    I agree, best to know what caused it first and when I asked the plaster guy what will prevent it coming back? He said "I don't know."

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    Mar 2011
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    Hazelton, PA
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    Re: Help! - New Plaster Blemish

    Acid wash will degrade your plaster, if you do decide to do one, do a "in pool" acid wash.

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    Re: Help! - New Plaster Blemish

    The TA represents "total alkalinity" and it is unlikely that it was 800 ppm. The "10.0" number could actually be the pH, because the pH in new plaster pools can go that high when the TA is low out of the tap. Also need the calcium hardness (CH) or the total hardness.

    From your responses, it sounds like the plaster has "gray mottling discoloration." Try goggling "gray plaster discoloration" and read up on that issue. It has nothing to do with water balancing. It sounds like the plasterer knows that it is his fault because he is offering an acid wash to fix. It is often just a temporary fix and not a good idea. If your state has a Contractor License Board, you might want to call and ask for an inspection.

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    Re: Help! - New Plaster Blemish

    WOW - thanks onBalance - you nailed it. Based on a few internet photo's, the grey mottling discoloration appears to be exactly what we have. I have pics but no time to upload. Went to get a full water test this morning:
    FAC = 3
    TAC = 0
    pH = 7.4
    TA = 100
    CYA = 50
    calcium hardness = 100 (tester guy said this was low, though not to be alarmed, and should be 200)
    TDS = 300
    Phosphates = 300 (high but he said don't do anything about it just yet)

    When I read about ineffective 'cures' of acid wash & torching, this is exactly what the plasterer guy said he would do so I interpret that as ownership of the issue. In other words, he probably knows exactly what went wrong and is looking for a quick way out. Sorry if i offended any contractors out there [my father was an honest used car salesman]: guilty until proven innocent.

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    Join Date
    Jul 2011
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    Arizona & California
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    768

    Re: Help! - New Plaster Blemish

    Graying and mottling of white plaster can look very different sometimes, but yes, I think that is the problem given your description. I am curious what city you live in? Trying to keep track of where these plaster problems are most prevalent.

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