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Thread: Calcium Chloride and Free Chlorine

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    efm1972's Avatar
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    Calcium Chloride and Free Chlorine

    I added 4 lbs of Calcium Chloride at 1PM ET today to raise the calcium level in my pool. Test results before adding the Calcium Chloride were as follows:

    FC = 4.0
    CC = 0.0
    pH = 7.6
    CH = 200
    Alk = 110
    CYA = 40

    Tonight, at 8:45PM ET, I started to test my water, but am not getting a reading for FC. Results as follows:

    FC = 0.0
    CC = 0.0
    pH = 7.6
    CH = 250
    Alk = 110
    CYA = 40

    Can adding Calcium Chloride impact FC test result (or other test results)? It was a nice sunny day here today, but typically, I do not fall below 1.5 ppm for FC and I test FC daily. Water temp got to 78 today and the water is crystal clear.

    Any insight as to why FC is zero would be much appreciated. I use 12.5% liquid chlorine was going to add enough to get to an FC of 7 ppm in the morning before I go to work and then retest again when I get home in the evening.

    Thanks
    18,500 gallons, DE filter, IG
    Onyx Ansylbrite (colored) plaster
    Jandy Pump 1.0 HP, Zodiac Filter (flow rate = 120 gpm)
    Installed May 2012

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    Butterfly's Avatar
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    Re: Calcium Chloride and Free Chlorine

    Sometimes adding CH will cause some clouding, but not effect tests. But, possibly FC if the bag contents had some contaminants/unwelcomed organics.

    With 40 CYA, keep FC between 3 and 7, and never below 3. Sounds like it has been dropping below the minimum.

    I suggest you do an OCLT to rule out/in organics.
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    Re: Calcium Chloride and Free Chlorine

    Any insight as to why FC is zero would be much appreciated.
    What is your "normal" daily FC loss?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    efm1972's Avatar
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    Re: Calcium Chloride and Free Chlorine

    Thanks. I decided to shock pool tonight and added 2 gal liquid chlorine. Will retest FC in an hour and then again in the morning.
    18,500 gallons, DE filter, IG
    Onyx Ansylbrite (colored) plaster
    Jandy Pump 1.0 HP, Zodiac Filter (flow rate = 120 gpm)
    Installed May 2012

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    efm1972's Avatar
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    Re: Calcium Chloride and Free Chlorine

    Normal FC loss is about 50%. If I start the day with FC = 4, it will usually be around 2 in the evening on a full sun day.
    18,500 gallons, DE filter, IG
    Onyx Ansylbrite (colored) plaster
    Jandy Pump 1.0 HP, Zodiac Filter (flow rate = 120 gpm)
    Installed May 2012

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    Mod Squad jblizzle's Avatar
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    Re: Calcium Chloride and Free Chlorine

    2ppm is too low for a CYA of 40ppm. Hopefully you pass the OCLT, but should maintain high FC levels going forward.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    efm1972's Avatar
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    Re: Calcium Chloride and Free Chlorine

    Thanks for the comments. Passed OCLT. I will now target to start day at FC of 6 or 7 ppm. That way (based on experience so far), I will end day around 3 ppm.

    Also, given all the rain we had in the northeast (Philadelphia), I have had to drain over 6" of water off pool over the past several weeks. I was out of reagent for testing CYA, and hadn't checked it since June 29th. I just got some more reagent and my CYA is now 30.

    Thanks again.
    18,500 gallons, DE filter, IG
    Onyx Ansylbrite (colored) plaster
    Jandy Pump 1.0 HP, Zodiac Filter (flow rate = 120 gpm)
    Installed May 2012

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