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Thread: Rain

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    what impact does rain have on pool water. Our pool is still open and we've recieved just over an inch of ran in 2 days. The water level was a little low before the rain (intentionally b/c rain was coming). Does 1 " rain equal 1" increase in pool water level? What happens to the pH.
    Grant and Jerri
    Liberty, NC
    New 18x36 vinyl liner pool with lighting and fountain

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    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Rain

    Does 1 " rain equal 1" increase in pool water level?
    Yes.....unless your decking is sloped incorrectly and runoff water is allowed to enter the pool.

    If you receive an inch of rain in a pool with an average depth of 4 feet, the chemistry will be diluted/changed by 1/48th......i.e. normal rain amounts have little to no effect.

    Again, if runoff enters your pool, you have a problem that will seriously affect your pool chemistry and, likely, the quality of your water.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Join Date
    Jan 2009
    Cupertino, CA

    Re: Rain

    However, people have reported that the agitation of the pool surface from rainfall has a similar effect as aeration, and made their pH rise. I haven't observed this, but I have a solar cover so the rain doesn't really agitate the pool water. My rainwater is definitely acidic but I haven't noticed any particular pH drop, either.
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    Cherie's Avatar
    Join Date
    Jul 2008
    Wylie, Texas

    Re: Rain

    Our pH dropped considerably while we had our solar cover on. Having read that the raindrops would raise the pH level, I took the cover off just before a big rain and sure enough, the pH fixed itself!
    32x16 buried Doughboy, 4' shallow - 7' deep
    Pentair Dynamo 1 hp, 2-speed - Pentair 150# SD40 w/zeolite (75#)
    One skimmer/two returns/Aquabot Turbo T2

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    Re: Rain

    Dont make any drastic changes to your pool after a rain for a few days. the pool will take a few days for the aeration (co2) to gas off and it will settle back out. It might change some, but just wait a few days.
    15k diving pool. Originally built in 1979. Rebuilt, except shell in 2008. mini pebble, faux rock slide with jumping rock, 2 1hp whisperflo pumps, tr140 sand filter. Flagstone coping. raised wall with stack stone.

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