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Thread: CH Level

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    CH Level

    Is the TF-100 CH test accurate when the CH is at a low level? The instruction says, I think, that when CH is low, divide the number in half - is this right? I thought that my water was soft - I've tested it with 2 local Leslie's and the results were both on the low side, like 180, but the TF-100 is twice of that. Is 1/2 of TF-100's number right?

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    Richard320's Avatar
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    Re: CH Level

    Believe your reading.

    Testing and Balancing Your Water mentions using a larger sample size when testing low levels. That's all. Make sure you use the correct multiplier for the sample size you're testing.
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    Re: CH Level

    Quote Originally Posted by Richard320 View Post
    Believe your reading.

    Testing and Balancing Your Water mentions using a larger sample size when testing low levels. That's all. Make sure you use the correct multiplier for the sample size you're testing.
    Yeah, I tested it again with the 25 ml water test and it came back at 250, vs 325 before. I didn't think 250 was that low where it could cause a difference this big.

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    Mod Squad pooldv's Avatar
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    Re: CH Level

    There are more detailed testing instructions here, Extended Test Kit Directions, that might help.
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    gtemkin's Avatar
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    Re: CH Level

    I don't know what the divide in half thing you've mentioned is but the standard and extended test specs for the TF-100 CH test are:

    25ml sample
    - 20 drops of R-0010
    - 5 drops of R-0111L
    - count R-0012 drops till color change
    - number of R-0012 drops times 10 equals CH reading

    10ml sample
    - 10 drops of R-0010
    - 3 drops of R-0111L
    - count R-0012 drops till color change
    - number of R-0012 drops times 25 equals CH reading

    I think the 10ml test is primarily to save on reagents so you can make the reagents last the season.
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    Re: CH Level

    Quote Originally Posted by pooldv View Post
    There are more detailed testing instructions here, Extended Test Kit Directions, that might help.
    Yes. Thanks you.

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    Re: CH Level

    Quote Originally Posted by gtemkin View Post
    I don't know what the divide in half thing you've mentioned is but the standard and extended test specs for the TF-100 CH test are:

    25ml sample
    - 20 drops of R-0010
    - 5 drops of R-0111L
    - count R-0012 drops till color change
    - number of R-0012 drops times 10 equals CH reading

    10ml sample
    - 10 drops of R-0010
    - 3 drops of R-0111L
    - count R-0012 drops till color change
    - number of R-0012 drops times 25 equals CH reading

    I think the 10ml test is primarily to save on reagents so you can make the reagents last the season.
    I am not sure what I got that impression from either. Probably from the comparison between my and Leslie's.

    I did the 2 tests 10 ml and 25 ml and got 325 and 250 - you would think that the results should've been closer. I'm trying to determine if I could use Cal-Hypo to help jacking up the CH level, but the results from the 2 tests are so different.

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    gtemkin's Avatar
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    Re: CH Level

    It is a test I've had problems with. I've found that using a Speedstir definitely helps and as you approach the color change point, you have to slow down with your drops 'cause the color takes a second or two to change and if you add drops too quickly, you may add a drop or two to your count that you didn't need to. It's real easy for example to add 2 drops on the 10ml sample that may not be necessary, which if not added would have put your 10ml test at 275; pretty close to on par with the 250 of the 25ml test.
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