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Thread: Does rainwater cause a significant drop in CYA?

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    Does rainwater cause a significant drop in CYA?

    Hi all...just curious if over the course of pool evaporation, a few small top ups, and a massive rainfall last night (filled pool water line to above the skimmer) would cause a 10-15 ppm drop in cya? Mine seems to be around 35 ppm at the moment, having measured 50 earlier in the season...
    20000 gallon, IG, SWG, Sand Filter, Hayward 1/2HP + Lorentz direct solsr PV pump

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    Mod Squad YippeeSkippy's Avatar
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    Re: Does rainwater cause a significant drop in CYA?

    The only thing that lowers CYA is water exchange.... so if you've had a mess of rain and had to drain some water you would have also removed some CYA too.
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
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    Re: Does rainwater cause a significant drop in CYA?

    But a substantial addition of water would technically dilute and reduce cya concentration, correct?


    68,000litre, IG vinyl, LorentzPS 600 Solar Pump & 1/2 HP Tristar, Sandfilter, Aquarite T-15 SWG
    20000 gallon, IG, SWG, Sand Filter, Hayward 1/2HP + Lorentz direct solsr PV pump

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    Mod Squad YippeeSkippy's Avatar
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    Re: Does rainwater cause a significant drop in CYA?

    I take back what I said.... I think there is a small miniscule loss of CYA to degradation over time in the chlorine...and yeah, if you're increasing the volume of water you'll be spreading that cya out over the larger amount so the concentration will be lowered. Usually people are removing excess water from the pool when the volume is too high.
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
    Our pool build--> Our Pool Solved Our Sloping Yard Skippy's Cheap Pool Cooler -->Skippy's New Fountain

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