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Thread: Does pH always read high when FC is high?

  1. Back To Top    #1

    Join Date
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    Does pH always read high when FC is high?

    pH 7.7
    FC 14
    CYA >40 (I treat it as if it were 50)
    TA 100
    CH 340
    Temp 44 degrees

    I am fighting mustard algae, so recently added FC to shock level to hit it hard while the water is cold. I made the mistake of not checking pH before adding the FC, but it last tested 7.8 which is right where I wanted it going into winter. So I'm a little confused as to current reading.

    My understanding of pH is that as the water cools and becomes colder, pH naturally rises? Also, my understanding of testing pH while FC is high is that pH may read *higher* than it actually is. I'm really trying to keep a close eye on CSI this winter. Should I be concerned with current pH reading?

    Edited to add temp reading
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    Re: Does pH always read high when FC is high?

    I ignore pH during the shock process.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    Re: Does pH always read high when FC is high?

    Quote Originally Posted by RobbieH
    I ignore pH during the shock process.
    Me too normally, but that's because I expect it to be higher than normal not lower...

    I'm about to raise the FC level again, so that will really skew the pH beyond reliability. You still think I should just ignore the pH reading?
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    Re: Does pH always read high when FC is high?

    Um, forgot to mention that I added calcium chloride this morning to raise CH level. I assumed that it would be pH neutral, but maybe not?
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    Re: Does pH always read high when FC is high?

    Calcium chloride is virtually pH neutral.

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