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Thread: OCLT Help

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    OCLT Help

    i got my fc to 19.5 last night and shut off my in line chlorinator. this morning i tested it and it was at 17.5. i know the instructions for shocking say to keep it at shock level until oclt is at 1 or less but is that the same at such a high initial fc level? in other words the percentage it went down is a lot less going from 19 to 17 than 4 to 2?? i'm trying to decided if i need to take the fc level back up to 20 or leave it alone. here are my results this a.m.

    fc = 17.5, cc = .5 (it's been .5 for a long time), ta - 160, ph = 7.2, cya = 50

    thanks for the help!
    Jeremiah Hough

    22,000 gallon, vinyl liner, chlorine, with auto cover

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    Butterfly's Avatar
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    Re: OCLT Help

    The OCLT is based on the only thing consuming the FC is organics in the pool. So, you do need to have a FC loss of 1ppm or less, regardless of the FC starting level.

    ETA: You are not done shocking.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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    Re: OCLT Help

    Take it back up. The 1ppm loss is valid if you go from 4-3ppm or 30-29ppm
    Dave S.
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    Isaac-1's Avatar
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    Re: OCLT Help

    Like they said, but just want to make sure your doing the test right, it should be done from dark at night until at or before first light in the morning.
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    Re: OCLT Help

    I did measure it after dark last night but it wasn't dark this mornig. i checked it about 6:30 am so it wasn't completely dark. I do have an auto cover so it was covered the whole time. that's another question i have - should i leave it covered or uncovered during the shock process.

    i have the fc back to 20 and holding. i will continue to test and make sure it stays there until dark tonight then perform the oclt in the a.m.

    i left my slide running all day and my ph is up to 7.6. i think that is where i want it but my TA is almost 200! from what i've read on here i need to add acid to lower ph back to 7.2 then aerate water until ph is back up?? how critical is TA at this level and is this the best way to lower it?? how long of a process is it? i'ts been about 160 for a month now.

    will the acid make the water cloudy like the ph+ does?
    Jeremiah Hough

    22,000 gallon, vinyl liner, chlorine, with auto cover

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    Mod Squad jblizzle's Avatar
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    Re: OCLT Help

    I do not think the cover matters.

    You can lower the TA following the Lowering Total Alkalinity. Acid lowers pH and TA, aeration raises pH ... repeat. It takes what it takes, but if you are diligent it could be only a few days. Do not have to worry about this while shocking since the pH test is inaccurate for FC > 10ppm.

    Acid should not make the water cloudy.
    Jason, TFP Moderator
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    Butterfly's Avatar
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    Re: OCLT Help

    I suggest you open the cover during the day to let the sun help burn off CC's.

    The TA can be addressed later. Just forget about the TA until you are done shocking. See red lines in my sig.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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    Re: OCLT Help

    The people at Walmart must think I'm crazy! I've bought 15 gallons of bleach this week. I'm getting frustrated. My water looked really good last week until I added ph+ (5lbs). It turned very cloudy and Is just now back to decent clarity. I'm not sure if I have algae but my oclt indicates I might. It seems like I have added a ton of chlorine. I'm going to perform the oclt again tonight. I really hope it's good in the morning. My water still isn't crystal clear. I'm not sure if it's due to the ph+ still breaking down or some sort of algae. I wish there was someone i could just talk to m
    Jeremiah Hough

    22,000 gallon, vinyl liner, chlorine, with auto cover

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    JasonLion's Avatar
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    Re: OCLT Help

    If the clouding happened right after you added the PH+, it is probably calcium clouding. Do you know your CH level? Also, what color is the water and is the cloudiness more cloudy or murky?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: OCLT Help

    It happened immediatly when I added it. It's not really cloudy now - just not crystal clear.

    How quick should fc go down on a normal sunny day?
    Jeremiah Hough

    22,000 gallon, vinyl liner, chlorine, with auto cover

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    JasonLion's Avatar
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    Re: OCLT Help

    Chlorine loss depends on a number of factors, but very roughly speaking with CYA around 50 you can expect to lose about half of your starting FC level per sunny day.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: OCLT Help

    i think i'm getting somewhere. oclt still showed a loss this morning but today fc seems to be holding better. cc is down to zero and water is looking better. fc is at 21.5. what fc level is safe to swim in with cya at 50?
    Jeremiah Hough

    22,000 gallon, vinyl liner, chlorine, with auto cover

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    Butterfly's Avatar
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    Re: OCLT Help

    We usually say safe up to shock level based on CYA level, which is about 20 FC for 50 CYA.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

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