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  1. #1
    Senior Member tiffany's Avatar
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    Theory on how to improve accuracy for calcium test kits.

    An on-line store suggested this idea for for improving the accuracy of the calcium tet kit:

    Calcium Testing Suggestion: Calcium testing in marine systems is fraught with difficulties. Test kits generally donít work well in the ranges that we run in reefs and many ions in marine water interfere with the kit. If your calcium level does not make sense, try diluting the aquarium water sample 50/50 with distilled, deionized or R/O water and testing. Multiply the result by 2. This will both save on valuable reagents in your kit and generally give a more accurate reading. (You may want to consult with the kit manufacturer to determine that doing this will give valid results with your brand of kit).

    What do you think?
    "The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
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  2. #2
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    The quote is from the Kent company, used by many stores who sells their products.

  3. #3
    Senior Member tiffany's Avatar
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    It may be from Kent's, but it was for another product, from a store that didn't sell Kent.
    Do you think it would work? and why would it make it more accurate?
    "The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
    - Albert Einstein (1879-1955)

  4. #4
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    I have used a bunch of test kits that gave that option. I'm not sure but I think even my current Salifert testkit has the option of doing it like that. Although I don't remember reading about the multiplying by 2 afterwards.

  5. #5
    Senior Member tiffany's Avatar
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    I don't see how halving the SW and adding RO then multiplying by 2 will give a different answer.
    And if you don't *2 then the results would surely have to be incorrect, you'd have to divide the result by two.
    Is that correct?
    "The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
    - Albert Einstein (1879-1955)

  6. #6
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    Originally posted by tiffany
    I don't see how halving the SW and adding RO then multiplying by 2 will give a different answer.
    And if you don't *2 then the results would surely have to be incorrect, you'd have to divide the result by two.
    Is that correct?
    If the test is more accurate at lower concentrations (which is what the package suggests) I could see why the method would work, but really otherwise you would reduce the accuracy of the test. Since the titration uses up reagents as you progress, and the concentrations should only affect the speed of the reaction I don't think it'd help. If you really wanted accuracy you could simply double (or triple, etc.)the original quantities of all reagents, and then each drop of the titrant would be equivalent to a half (a third, etc.) drop in the initial test - this would allow a more accurate determination of calcium but probably isn't necessary, and would use your kit twice (thrice, etc.) as fast.

  7. #7
    Senior Member tiffany's Avatar
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    "The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
    - Albert Einstein (1879-1955)

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