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Thread: Calcium stains on dark plaster

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    Join Date
    Apr 2014
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    Bakersfield, California
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    Calcium stains on dark plaster

    Replastered pool with dark grey color about 1 year ago. Using TFPC method. In November CH was at 800 and PH went high for about a week and resulted in calcium stains that a very noticeable. I am considering having an acid wash on 1 year old plaster to remove stains.

    Will acid wash remove all calcium stains?
    What affect will this have on dark plaster?
    Will this cause any long term damage to pool finish?

    Here are my water readings:

    FC=4
    PH=7.4
    TA=60
    CH=300
    CYA=30
    20K gal colorscapes dark gray plaster, no SWG, BBB method, variable speed hayward ecostar pump, pentair cartridge filter, hayward navigator cleaner.

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    Mod Squad zea3's Avatar
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    Re: Calcium stains on dark plaster

    Draining and doing an acid wash may be more than it needs. I do know an acid wash will shorten the life of the plaster. I'm not sure if an acid wash will give the results you want on dark plaster. Have you tried lowering the pH to between 7.0-7.2 and keeping it there to see if the stains go away?
    TFP Moderator
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    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
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  3. Back To Top    #3

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    Re: Calcium stains on dark plaster

    No i have not tried that. However i would be willing to try it. What is the procedure? And for how long do i leave the PH at 7.0?
    20K gal colorscapes dark gray plaster, no SWG, BBB method, variable speed hayward ecostar pump, pentair cartridge filter, hayward navigator cleaner.

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    duraleigh's Avatar
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    Re: Calcium stains on dark plaster

    Leave it down at 7.0 until you give up. Slowly, it should have some effect. Monitor the pH absolutely every day. Keep it at exact;ly 7.0....lower it if it goes to 7.2. It won't cost much at all but will take close supervision.

    Take a "before" picture now so you can compare in a couple of weeks. Success is not guaranteed, of course, but if you are diligent, I think you can get a lot, if not all of it.

    If you have a lot of it right at the waterline, I would lower the water level a couple of inches and tackle it with a scrub brush and a 3:1 dilution of muriatic acid. You know it is working if you see foam on the buildup. might have to go 2:1 to really get it going.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  5. Back To Top    #5

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    Re: Calcium stains on dark plaster

    How often should i brush plaster surface and do i need to use a steel brush?
    Concerned about steel brush scratching surface.

    Will i get better results lowering PH to 6.8?
    20K gal colorscapes dark gray plaster, no SWG, BBB method, variable speed hayward ecostar pump, pentair cartridge filter, hayward navigator cleaner.

  6. Back To Top    #6
    Hemess's Avatar
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    Aug 2012
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    Norman, OK
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    Re: Calcium stains on dark plaster

    I need to do this as well! I have calcium all over my dark plaster and on my tile.


    28,000 IG, gunite, IntelliChlor IC40 SWG with SPA,
    Intellichlor/VS Pentair
    Norman, OK

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