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Thread: brownish dust - guano?

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    Join Date
    Jul 2016

    brownish dust - guano?

    I have been dealing with the same problem, and since we have pine tress around the pool, I thought it could be dust or dirt coming from them. However, I just spoke to someone at my local pool store and they told me most likely it is guano, that there are bats in those tress, but to me it still looks more like dust or sand. I had the sand replaced, vacuum every day, and after a two or three hours the brown spots are back! I have to say though, after changing the sand in the filter and treating the water properly, it looks much better, but still dealing with brown spots. Had any of you heard about guano in the pool?

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    Mod Squad JVTrain's Avatar
    Join Date
    Feb 2014
    Central Minnesota

    Re: brownish dust - guano?

    Most importantly, do you have recent test results, from a recommended test kit? Pool School - Test Kits Compared

    Guano is low on the list of possibilities. Bat guano typically dries in solid masses on the ground or on a surface and will only become dust/airborne if it is intentionally disturbed. I think pinning dust on the bottom of the pool on guano is just another typical load of guano from pool store advice.

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    Join Date
    May 2016
    Troy IL

    Re: brownish dust - guano?

    I have light brown very fine dirt build up in my pool on a daily basis. I notice it mostly because it collects in the seams of the vinyl liner. I live in a fairly rural area, so I'm pretty certain mine is just from dust in the air. It reminds me of silt in a river. My guess is that's what you've got also.

    20,000 gallon IG Vinyl
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    Thimble's Avatar
    Join Date
    Apr 2013
    Wichita, KS

    Re: brownish dust - guano?

    If it was guano, I'd think your chlorine demand would be terribly high, along with your CC readings.

    My guess would be dirt or dead algae. Try the DE in your sand filter trick, see if it doesn't go away or is reduced.
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