Testing Calcium

Discussion in 'Water Parameters and Additives' started by Hill, 8 Dec 2007.

  1. Hill

    Hill

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    Hey guys maybe someone can help me.

    I Have Alkalinity and Calcium Lemotte test Kits. I find the Alkalinity very accurate. But I am battling with the Calcium. I cannot get an accurate reading. My last test had a reading of 500 odd ppm. And I never added Calcium.

    Those of you not familiar with the test. It works as follows.
    You add 1ml SW to the test vial. Then you fill up the test vial with distilled water to the 12.9ml mark. I use my R/O D/I water. Just checked a reading of 000ppm. Then 6 drops of Sodium Hydroxide Reagent. Mix. Add a little tablet (Calcium hardness indicator). Swirl around solution become red. Fill titration syringe to zero mark. Add to solution until it turns blue. Multiply by 5.16 to get reading.

    Even my NSW seems to read high. like 460ppm.
    Two concerns. When filling a test vial to 12.9ml. Where must the line be? The solution has a curve where it is attrated to the sides of the vial. Miniscus? If I recall correctly from school the line must be at the bottom of the curve ie the lowest point when looking through the vial. Is this correct?
    The bottle those little tablets comes in has quite a bit of loose powder at the bottom. Maybe one or two tablets worth. I can't tell if it is a complete tablet that disintigrated or just slight abrasion to all the tablets from transport. Would this affect the reading?
    The drops from the titration syringe are quite large. and equates to roughly 8x5.16 ie about 40ppm. Any ideas on how to get this more accurate?

    Any suggestions welcome. Or Phat would you like to come teach me how its done. You being the Lemotte expert.
     
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  3. Tridan

    Tridan

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    I only have the lamotte kh and am happy with it i have used Phats calcium test a few times and done exactly as you said.

    Your nsw is it from kwelera if so a possible link is that it has a lime base around areena area so that might elevate the calcium levels a bit, not sure tho just a guess.
     
  4. Hill

    Hill Thread Starter

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    Agree but I just find it difficult to get the same reading on different samples.
     
  5. Tridan

    Tridan

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    yeah i know the feeling thats why i spent the extra bucks and bought lamotte, now i am worried about buying the ca test. might aswell keep the serra and api, the api is accurate after i read up about it there are a few tricks. Good luck,


    Sorry i havenot contacted you i have been really sick, will do so soon tho.
     
  6. Alan

    Alan Admin MASA Contributor

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    Sorry Hill cant help you out here as i have only used Tropic Marine, why not get somebody to check results for you.
     
  7. irie ivan

    irie ivan MASA Contributor

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    yes!

    Also using these kits, and I find the calcium one a bit tricky too. Most importantly to help spot the colour change is to do it under the right lighting conditions! Do it away from your tank, as we use blue lights, which interferes with our judgement of colour.
    Do it under normal cool white flourescents against a white background.
     
  8. Hill

    Hill Thread Starter

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    Thanks will try that too.
     
  9. mandarinman

    mandarinman

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    dang and we do this for relaxation?
     
  10. Hill

    Hill Thread Starter

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    Eventually worked this test out. Found most of the problem was that I was not using the pink nozzle on the front of the syringe. It makes the droplet size much smaller. Also holding reagent one vertically makes the drops size more uniform.

    So in the end I am really happy with the test kit now that I have worked it out.
     
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