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Thread: Calcium Hardness in replastered pool

  1. Back To Top    #1

    Join Date
    Apr 2014
    Bakersfield, California

    Calcium Hardness in replastered pool

    Just had my pool re-plastered about 1 month ago. Went with dark color quartz finish. Start-up pool guy did a great job and his 1 month startup service has been completed. I am now on my own for maintaining pool chemicals and chemistry. On pool service guy's last week (4th week) he stated Calcium Hardness was at 235. This was on Thursday. On Saturday, Leslie's tested water and Calcium Hardness was at 240. I also bought my own test kit. Today (Monday) i tested water and Calcium Hardness is now at 380. Leslie's also tested water today and confirmed Calcium Hardness is at 380. I am a little confused as to why the Calcium Hardness has gone up so quickly when water is just over a month old. Could i be getting false readings? Is there a certain time of the day to get the most accurate water chemistry readings? My pool start-up guy had said not to worry about the Calcium Hardness reading unless it went over 450 and that i would not have to drain and refill until the winter. Will i need to drain some water sooner to maintain Calcium Hardness within range and avoid possible calcium scaling on my new finish? Here are my water test readings as of today:
    FC = 3
    PH = 7.8
    TA = 90
    CA = 385
    CYA = 50
    Using 3 in. trichlor tabs in floater (part of startup pool guy's process). However, considering switching to liquid chlorine as primary source of sanitizer.

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Calcium Hardness in replastered pool

    What test kit gives readings accurate to 5 ppm? You don't need that kind of accuracy. CH can come from curing plaster or chlorinating with Cal-hypo, or hard fill water and a lot of evaporation. Insufficient mixing with a drop test will also make it read artificially high.

    If your CYA is really 50, you'd better decide fast if you want to keep using trichlor, or you'll be draining water whether you like it or not to reduce the CYA buildup. Your FC is already below the suggested minimum for 50 CYA.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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  3. Back To Top    #3

    Re: Calcium Hardness in replastered pool

    With a calcium hardness increase of 140 ppm in 2 days, I think that either someone added calcium chloride or there is a test error.

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