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Thread: Where did my CYA go?

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    Join Date
    Jun 2011
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    Ridgefield, CT
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    Where did my CYA go?

    We opened the pool last week and I did an initial test using the Taylor 2006. I had no discernible CYA reading (filled the tube to the top and had no problem seeing the black dot). I finished last fall with a CYA in the 30s. Is it possible that the accumulated rainfall over the winter and spring diluted the water that much? We have a hole in our winter cover so we do take on some water during the winter.

    I don't think this is the first winter that the CYA has dissipated. We purchased our house from someone who used tri-chlor as far as I know (he left quite a bit behind). Yet, I still needed to add CYA last spring as I was pretty low. I ended up adding enough CYA to raise the level to about 40-45 ppm. And I stiil finished the summer with less than that after the various rainfalls and splash outs.
    33,000 gallon plaster pool
    Jandy L-Series -CL580 Cartridge Filter

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    linen's Avatar
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    Jul 2010
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    Twin Cities, MN
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    Re: Where did my CYA go?

    Quote Originally Posted by yossarian
    Is it possible that the accumulated rainfall over the winter and spring diluted the water that much? We have a hole in our winter cover so we do take on some water during the winter.
    If it dropped you cya level below 20 ppm, that is also below where the taylor cya test can measure. In addition, CYA is can be lost over the winter. The current theory is that this caused by an anaerobic soil bacteria that can grow when the pool is covered and FC levels are zero.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Join Date
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    Re: Where did my CYA go?

    Quote Originally Posted by linen
    Quote Originally Posted by yossarian
    Is it possible that the accumulated rainfall over the winter and spring diluted the water that much? We have a hole in our winter cover so we do take on some water during the winter.
    If it dropped you cya level below 20 ppm, that is also below where the taylor cya test can measure. In addition, CYA is can be lost over the winter. The current theory is that this caused by an anaerobic soil bacteria that can grow when the pool is covered and FC levels are zero.
    Does anaerobic soil bacteria look like algae by any chance.

    It would seem that, for people like us in the Northeast, we can get away with using trichlor much more often since we can lose CYA over the winter. Last year, I was very skittish about using it for a 2 week vacation in August or for an occasional long weekend away from home. This year, that doesn't concern me at all since I can seemingly afford a rise of ~20 ppm during the course of the summer (assuming I start in the 30-35 range).
    33,000 gallon plaster pool
    Jandy L-Series -CL580 Cartridge Filter

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    linen's Avatar
    Join Date
    Jul 2010
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    Twin Cities, MN
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    8,649

    Re: Where did my CYA go?

    Quote Originally Posted by yossarian
    Does anaerobic soil bacteria look like algae by any chance.
    I think it looks like little elves that replace your water while you sleep

    Quote Originally Posted by yossarian
    It would seem that, for people like us in the Northeast, we can get away with using trichlor much more often since we can lose CYA over the winter. Last year, I was very skittish about using it for a 2 week vacation in August or for an occasional long weekend away from home. This year, that doesn't concern me at all since I can seemingly afford a rise of ~20 ppm during the course of the summer (assuming I start in the 30-35 range).
    It does seem that way...I have noticed that here too, though this year I still had cya when opening. Go figure. A theory here...trichlor puck users (using blind with out testing cya) may get by for a summer or a few summers, but then a winter like this last one (for me) comes along, they do not loose as much cya and then they are in trouble come end of July. Of course, they have no idea what their cya level since they do not test for it, so they do not know this is going on.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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