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Thread: Chemistry issues in winter pool closing NW Minnesota

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    Chemistry issues in winter pool closing NW Minnesota

    For years our practice has been fairly simple. We lower the water to about 1/2, blow out the pipes and use some RV antifreeze. It has been perfectly successful to prevent any damage, however in the spring the pool is very stained with algae and worse actually is the staining from leaves. Our practice has been to completely drain in the spring and power wash with enough pressure to more or less rip off the paint. We then repaint for our roughly 3 month summer season. The usage is really just 3 months due to the high cost of heating and the users loose interest once the summer season is over. Before my time the group has tried covering with plastic sheeting, but I am told it did little good.

    My question is roughly can we chemically prevent at least the algae and possibly the leaf staining, at least to the point where we could just clean up the surface, with lower pressure perhaps, so as to avoid repainting each season. The rubber based chlorinated paint is getting quite expensive, our pool is 66,000 gallons gunite so it requires a lot.

    Here is what I am considering. Adding quite a bit of dichloro to the half filled pool, and perhaps balancing it with soda ash. The reason I am thinking soda ash balancing ph might be needed is to prevent damage to piping, although most piping is heavy black plastic I suspect the lower drain may be metal, buried under the pool of course. If adding soda ash could prevent damage it would be a cheap preventative.

    If my ideas make sense does anyone have any idea of the quantity of each required.
    66,000 gal gunite private membership pool in NW Minnesota

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

    Re: Chemistry issues in winter pool closing NW Minnesota

    Welcome to TFP!

    Covering the pool will prevent leaf stains and greatly lower the chances of algae getting started. Without a cover, I doubt that there is anything you can do.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Chemistry issues in winter pool closing NW Minnesota

    OK, that is probably right. Seems doubtful that even with a high level of chlorine it would suppress algae for the entire off season. I am curious why the paint is labeled as 'chlorinated rubberized'. Apparently doesn't kill algae!

    As to a cover, the original group which built the pool made it a very odd's pretty..but covering it is so difficult that we gave up. To save heating costs and such we may have to revisit this issue in the future.

    To cover it this off season I could imagine getting a big roll of plastic film, such as the farmers use to cover large hay stacks for example. It would be a throwaway in the spring, but maybe the cost would be justified. What I hope it would achieve would be to keep the leaves and dirt on top of the plastic. Of course we have to pump the pool down below the plumbing, but retain enough water to keep ground water from trying to float the pool and damaging it. That is worked for 40 years.

    Any suggestions are appreciated.
    66,000 gal gunite private membership pool in NW Minnesota

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    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Chemistry issues in winter pool closing NW Minnesota

    The leaf stains are organic and will slowly disappear in the presence of elevated chlorine levels.

    Close the pool as you usually do, read the article in Pool School on Closing, and bring the FC to shock value before you close.

    Next Spring, physically remove all the solids you can from the pool and then shock your pool by following the directions EXACTLY in Pool School and then hold your chlorine at twice the suggested level until the stains disappear......usually less than a couple of weeks. Brushing will also help.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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