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Thread: Black stain on plaster

  1. Back To Top    #1

    Join Date
    Aug 2012
    Location
    Fort Worth, TX
    Posts
    83

    Black stain on plaster

    Black algae is what caused me to find troublefreepool and BBB about 10 months ago.
    Since starting BBB I have not seen a trace of algae and my water is always crystal clear. I have carefully maintained my chlorine level.

    Yesterday, I noticed a triangular shaped, black stain on a side surface. It is sitting right on a hairline crack. ( the pool is almost 20 years old).
    It's about 1" long and 1/2" wide. It looked exactly like black algae, but it didn't feel like it. Black algae feels waxy. This didn't. It felt just like the plaster.

    I tried rubbing it with a chlorine tab, then a vitamin C tablet and they didn't phase it. I also brushed it hard with a steel brush- no help.

    I'm assuming it's some kind of mineral stain. I'm not going to worry about it unless it starts growing. It's 1' below the water line and if worse comes to worse I can drain down to it and scrub it with acid.

    Any ideas about what it is?
    10,000 gal / Plaster / Cartridge Filter / 1 1/2 HP pump motor/ TF-100 test kit.

  2. Back To Top    #2
    Butterfly's Avatar
    Join Date
    May 2007
    Location
    South Carolina
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    10,045

    Re: Black stain on plaster

    Got a pic for us?

    Try rubbing with a pumice stone?
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  3. Back To Top    #3

    Join Date
    Aug 2012
    Location
    Fort Worth, TX
    Posts
    83

    Re: Black stain on plaster

    Quote Originally Posted by Butterfly View Post
    Got a pic for us?

    Try rubbing with a pumice stone?

    I haven't tried a pumice stone. I'll try that today after work.

    Pic? I'll try to get one posted in the next few days. I'm not too savvy on that, but I'll figure it out. I need to anyway.
    10,000 gal / Plaster / Cartridge Filter / 1 1/2 HP pump motor/ TF-100 test kit.

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