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Thread: new numbers after water replacement

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    Join Date
    Aug 2009
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    Chandler, AZ
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    new numbers after water replacement

    OK, after the help I received troubleshooting my pool light, I just replaced 85-90% of my water with our hard southwest tap water. Last fall I posted with very high CYA water left over from the last owner of this house. Here are the current numbers:

    FC = 0.5 or less
    CC = 0.5 or less
    TA = 130
    CH = 390-400
    CYA = 40
    PH = 7.8

    By my novice judgment, I need to lower my PH a bit and it might not hurt to shock the pool to a FC of 16 given that this is new water and my CC and FC readings.

    Thoughts?

    Thanks so much!
    ~12k gallon in-ground pool, PebbleTec surface, sand filter, The Pool Cleaner (2WD)

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    duraleigh's Avatar
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    Apr 2007
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    Re: new numbers after water replacement

    Lowering the pH is a good idea but I see no reason to shock. Simply bring your FC up to about 4ppm (soon) and test it pretty often until you figure out how to keep it stable around 3-5ppm.

    As long as your water looks nice and your CC's are .5ppm or less, you are good to go. With your CH at the top end of OK, it will be helpful to keep your pH down around 7.4 but it sounds like you already know that.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Chandler, AZ
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    Re: new numbers after water replacement

    Quote Originally Posted by duraleigh
    Lowering the pH is a good idea but I see no reason to shock. Simply bring your FC up to about 4ppm (soon) and test it pretty often until you figure out how to keep it stable around 3-5ppm.
    OK good, I will do just that after work tonight and keep a close eye on it for the next week or so. The water is still pretty cold (~67 degrees) so I expect it to be pretty stable until things warm up and we start using it again. At this point the water looks remarkably clear, so I suspect I am in good shape for now.

    Quote Originally Posted by duraleigh
    As long as your water looks nice and your CC's are .5ppm or less, you are good to go. With your CH at the top end of OK, it will be helpful to keep your pH down around 7.4 but it sounds like you already know that.
    I was thinking of lowering the pH down to 7.6 "just because" 7.8 felt a little high. I actually didn't know about the relationship between higher CH and keeping pH a little lower. Could you point me in the right direction for information on that?

    Thanks a lot to everyone here. I feel empowered to understand and maintain the chemistry and solve problems on my own after doing a lot of reading on this board and pool school, plus fiddling around with my own pool and getting some very helpful advice here. Thanks again.
    ~12k gallon in-ground pool, PebbleTec surface, sand filter, The Pool Cleaner (2WD)

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    frustratedpoolmom's Avatar
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    May 2007
    Location
    SWSuburban Chicago, IL
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    11,963

    Re: new numbers after water replacement

    Quote Originally Posted by pebble.pool.fool
    Could you point me in the right direction for information on that?
    Here's a starting point:

    http://www.troublefreepool.com/pool-...alcium_scaling

    You can also use the Google Search feature (bottom left corner) and read the various topics that have come up in the past, several good discussions have taken place.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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