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Thread: CH sample tube level?

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    CH sample tube level?

    I have a TF-100 test kit and the instructions says to fill clear plastic cylinder to 10 ml mark. I previously printed out a pdf file forum and says to fill to 25 ml mark (10 ml) The open and close paren use for very high CH. My CH is ~ 280. Should I fill to 10 or 25 ml mark? I must be misreading or interrupting instructions incorrectly. Thanks
    28,000 gallon IG pool, plaster, built approx. 1970.
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    Texas Splash's Avatar
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    Re: CH sample tube level?

    Both the TF-100 card and Extended Test Kit Directions show 10ml. Please use the 10ml mark. Have a nice day.

    PS ~ We are required to multiply our drops by 25. Perhaps that was the confusion? Or.... please see next two replies.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Re: CH sample tube level?

    You can use either. With the 25 ml sample each drop equals 10 ppm, and with the 10 ml sample each drop equals 25 ppm. Generally knowing your calcium level to the nearest 25 ppm is good enough.

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    Texas Splash's Avatar
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    Re: CH sample tube level?

    I missed the note at the bottom:
    If you expect that your CH level is very low, you can do the test so that each drop is 10, instead of 25, to get some extra precision. Use 25 ml of pool water, 20 drops of R-0010, 5 drops of R-0011L, and multiply the number of drops of R-0012 by 10 to get your CH level.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Patrick_B's Avatar
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    Re: CH sample tube level?

    The smaller sample size is suggested to save reagent and time running the sample. 10 isn't wrong, but at 280 PPM I would prefer running the 25 ml sample if it were my pool. It's not critical, but you do lose accuracy with the smaller sample size, and 25 ml sample won't use much reagent anyway. It holds true for all the reagents, because you aren't spending much time or money compared to the value that accurate testing and balancing brings to the table.
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