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Thread: Ok to put rain water into pool?

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    Join Date
    May 2009
    Seminole, FL

    Ok to put rain water into pool?

    Got some big barrels my wife uses to collect rain water for watering plants and such - But she doesn't use nearly as much as they hold. Is it OK to put some of the water into the pool to keep it full? I heard it may drop the pH and such but are there any other downsides? Obviously it rains into the pool so it can't be THAT bad..
    ~13000 inground plaster
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    dmanb2b's Avatar
    Join Date
    Apr 2009

    Re: Ok to put rain water into pool?

    I would say go for it....just be sure to rebalance your water chemistry after the added water has been recirculated for 30 mins
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    Join Date
    Jan 2009
    Cupertino, CA

    Re: Ok to put rain water into pool?

    Just for grins I tested my rainwater last winter. pH was low (read as 6.8, hard to say what it was really), TA and CH were zero.
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    gtm's Avatar
    Join Date
    Aug 2008
    St. Petersburg, Florida

    Re: Ok to put rain water into pool?

    Like paulr I also couldn't resist using my kit on rainwater and found the pH to be off scale low. Did some reading and found that ""pristine" rainwater is like 5.6; lower in polluted areas. But my experience says it doesn't matter.

    Over the past two weeks I've gotten about 4 inches rise in the pool due to rain, which is about 7% of my total volume. The pH and TA haven't changed measurably.

    I'm sure one of the chem experts could explain it properly, but I think the key point is that the pool is a buffered system, so the pH change is much smaller than simple dilution would suggest.
    15,000 gal. IG fiberglass pool w/ 1 hp Hayward Max-Flo and 250 lb. Hayward sand filter
    Located in St. Petersburg, Florida, and enclosed in a birdcage

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Ok to put rain water into pool?

    The TA level of rainwater is extremely low. Because of that the pool water, which has a much higher TA level, influences the final PH far more than the rain water does.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    AnnaK's Avatar
    Join Date
    Jul 2007
    Eastern Pennsylvania

    Re: Ok to put rain water into pool?

    You might have some algae in rain water that's been sitting in a barrel but heck, we know how to deal with algae, right? I'd use it and then rebalance the water.
    — AnnaK —

    12,000 gal AGP, Hayward sand filter, Pentair 2-speed pump, timer.
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