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Thread: Chlorine Demand

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    gfritz1 is offline Registered+ Thread Analyst gfritz1 0
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    Question Chlorine Demand

    Been three years since posted but the chlorine demand is back. Inground-DE-Vinyl- 23000 gal .Started out season good but now cannot get a FC reading above .5 .Eating chlorine at rapid rate .Last readings 7.0 PH ,.2FC,.2 CC,138 Alk, 80 cya, 258 hardness. Had chlorine demand test 4 weeks ago and came back 92 bags to add . I took option of partial drain and took water down 15 inches. Still same issue but new chlorine demand now says 33 bags. Water is perfect clear and has been . Options:
    Do teh 33 bags but what type of shock ????
    Do partial drain and another test and then shock? What type of shock?
    swithch to Pristimne Blue ?
    Fill in pool ?
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    Default Re: Chlorine Demand

    NO to your last two options --- using Pristine Blue and filling in the pool!

    Please fill your pool's information into our pool chart and that will make it easier for us to help.
    Pool Chart Entry Form
    Pool Chart Results
    What kind of shock is it -- meaning ingredients. How high have you been taking the chlorine when you add it? Have you had a recent algae bloom?

    Welcome back to the Pool Forum, by the way!

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    gfritz1 is offline Registered+ Thread Analyst gfritz1 0
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    Default Re: Chlorine Demand

    Did the Pool Chart Entry Form but could not fill out Pool Chart Results Form for some reason .
    I rotate shoch between dichlor-cal hypro-lithium -chlorine free to try to avoid cya increase as in past using hth cal was over 120
    Using tri chlor tabs in a side style chlorinator
    No algae bloom as pool is crystal clear . I have a chart (excel with all my readings from opening to now )anyway of posting or emailing?
    usage on pool is low -mostly adults and about 1-1.5 hrs per day

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    Default Re: Chlorine Demand

    You aren't supposed to fill out the Pool Chart results, just the entry form.

    I don't know of a way to post an excel spreadsheet. For now, can you just give us the most current readings and tell us the date they were taken?

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    gfritz1 is offline Registered+ Thread Analyst gfritz1 0
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    Default Re: Chlorine Demand

    IEntry Form is filled out .Recent results 7/12
    CYA 70
    PH 7.1
    Alk 138
    Hard 258
    FC .2
    CC .2
    TC .4

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    Default Re: Chlorine Demand

    I would not use either dichlor or cal-hypo, because your calcium and CYA are both already high. I would use plain, unscented bleach. In 23K gallons, each 3 quarts of 6% bleach will raise your FC by roughtly 2 ppm. With a CYA of 70, you need to raise your chlorine to shock level, which for a CYA of 70, would be 20 ppm. To get from 0 to 20, that means 7.7 gallons (8 to be on the safe side). You need to test the water as many times a day as possible, and add whatever amount of bleach is needed to get back up to the 20 ppm. Hold it there (the more consistent you are, the faster you'll get there) until you can measure chlorine at night and again the next morning before the sun is on the pool, and not lose more than 1 ppm of chlorine in that time. Then you can let it drift back down, but never below 5 ppm.

    I suspect you have algae trying to bloom, and you have been chlorinating enough to keep it at a standstill, but not enough to kill off what you can't see. If you'll shock as described above, it should correct the problem.

    I wouldn't use any more stabilized chlorine--no dichlor powder or trichlor tabs. I would switch to plain bleach for your chlorination to keep those CYA levels from getting any higher.

    Janet

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    Default Re: Chlorine Demand

    To add to the advice that Janet gave you above, your pH is a little low. Use some 20 Mule Team Borax (laundry aisle at Walmart) to bump it up a little. Aim for 7.4-7.6 but anywhere 7.2-7.8 is ok. Start by adding a half a box slowly to the skimmer while the pump is running. Retest after a couple of hours. NOTE --- You cannot get an accurate pH reading when your chlorine level is high. Adjust your pH a little first because with a chlorine level of 20, you won't be able to get a true pH reading.

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    Default Re: Chlorine Demand

    Can I use Lithium shock as have a pile of it?

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    Default Re: Chlorine Demand

    I don't think it will hurt anything to use it, and it will add chlorine, so yes, go ahead.

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    gfritz1 is offline Registered+ Thread Analyst gfritz1 0
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    Default Re: Chlorine Demand

    Janet - will return from work in kY on Friday and will address the pool.Part of my issues is have been working in KY away from home and treating the pool remotely . I am debating about doing a partial drain on my return to get the cya down a little realizing that it is costly . Whats the advantage of doing this or not doing it? I think the cya is probally higher since these readings as have been eating tri clor tabs at a rapid rate

    I am looking at using lithium shock since have a supply but unsure enough to raise the leave to 20 ppm and maintain it. Where can I find a formual to calculate the amount needed to bring my pool to 20 at 23000 gals? If I understand correctly I need to start at night and keep feeding the chlorine to keep at 20ppm until the next morning? Sounds like I raise to 20ppm and keep measuring and adding as it drops to get above 20 for a 12 hr period? Then keep at 5 ppm
    As for not using tabs you say use bleach .What amount and at what frequency ? Thanks as cant wait to get this behind me. One more questions A&H Baking soda compared to Borax or to PH+ what is the difference as I really need to get my PH up

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