Understanding Testing

Discussion in 'Test Kits, Controllers, Reactors and Dosers' started by leslie hempel, 2 Mar 2011.

  1. leslie hempel

    leslie hempel Moderator MASA Contributor

    Joined:
    7 May 2007
    Posts:
    14,546
    Likes Received:
    287
    Location:
    Gonubie East London
    I want your opinions on the following statement

    “Test Kits are made to test perfect water conditions and if there is a problem with Cal for example it doesn’t mean calcium is the direct problem”

    Nice clean debate on testing and the test kits accuracy and ability to evaluate if there is a problem.

    In my experience of testing (which I feel is pretty extensive as I tested water almost daily when working at various LFS’s) I tend to believe the kits we use cannot always accurately determine what the problem with our water is..(should there be one)

    Take the scenario of calcium, magnesium alk triangle. By testing one of those values and finding a fault it doesn’t necessarily mean the item tested for is the problem, but rather one of the 3 (perhaps all) are out of balance and hence the testkit is reading an inaccuracy?

    I do believe testing is very important to keeping things stable and identifying a problem. But, and with opinions offered here im hoping to perhaps understand things a little better through another opinion..

    Comments welcomed..
     
  2. AdS Guest




    to hide all adverts.
  3. leslie hempel

    leslie hempel Thread Starter Moderator MASA Contributor

    Joined:
    7 May 2007
    Posts:
    14,546
    Likes Received:
    287
    Location:
    Gonubie East London
    i am reffering to testing using reagents and not electronic testing but for the sake of interest perhaps these should be included aswell?
     
  4. robertkukla

    robertkukla

    Joined:
    23 Mar 2010
    Posts:
    969
    Likes Received:
    14
    Location:
    Minnabron , JHB
    tagging along i am very interested in how the one can affect the other especially the calcium scenario
     
  5. lIghty

    lIghty

    Joined:
    3 Nov 2007
    Posts:
    5,053
    Likes Received:
    52
    Location:
    Westville, Durban
    Good topic Les!

    Test kits are not 100% accurate IMO, not for the price we pay for them. But I would say they are more than good enough for what we need them for.

    As for your eg. I don't think the test kit is reading inaccurately. It's telling you the parameter of the water, it's them up to the user to find out why he is getting such a reading.
     
  6. lIghty

    lIghty

    Joined:
    3 Nov 2007
    Posts:
    5,053
    Likes Received:
    52
    Location:
    Westville, Durban
    Oh, and AFAIK all test kits have a "working range" of parameter.

    Eg, the test kits we use for say No3 probably wouldn't work while test for No3 in water that has a pH of 4 or something.
     
  7. clinton stanford

    clinton stanford

    Joined:
    11 Mar 2009
    Posts:
    2,210
    Likes Received:
    4
    Location:
    East London
    this is going to be interesting....good topic Les;)
     
  8. leslie hempel

    leslie hempel Thread Starter Moderator MASA Contributor

    Joined:
    7 May 2007
    Posts:
    14,546
    Likes Received:
    287
    Location:
    Gonubie East London

    good point, another question worth asking, and im not trying to knock any brand here...

    but if a test cannot accuratley pinpoint the problem IE. calcium is out by X and it is calcium not one of the 3 in the triangle (i am excluding PH but it is married to this equasion) is it worth buying an expensive test kit over a cheap one?

    obviously the range of testing must be taken into account IE: PPT (parts per thousand) vs PPM (parts per million)

    PPM will give a greater scope to if there is a problem somewhere by being more sensitive or should i say broad in its readings...

    just throwing my thoughts out there......
     
  9. dallasg

    dallasg Moderator MASA Contributor

    Joined:
    14 Dec 2008
    Posts:
    16,771
    Likes Received:
    582
    Location:
    Sandton
    i believe test kits that use liquids or powders to be not as accurate as those that use tablets etc, i mean when they say add 2 drops some drops are bigger than others etc, and powder scoops can vary as well, but as a guideline they are good.
    electronic testing is better and getting a sample tested my a lab is the best :)

    i wish more test kits would use tablets as then the required reagents are present in the correct quantities, or am i off base?
     
  10. leslie hempel

    leslie hempel Thread Starter Moderator MASA Contributor

    Joined:
    7 May 2007
    Posts:
    14,546
    Likes Received:
    287
    Location:
    Gonubie East London

    so if your water has to be semi accurate to get a reading what are we testing for:tt2:
     
  11. leslie hempel

    leslie hempel Thread Starter Moderator MASA Contributor

    Joined:
    7 May 2007
    Posts:
    14,546
    Likes Received:
    287
    Location:
    Gonubie East London
    people often dont understand that there is a chain reaction wrt water parameters..

    "temperature is King" all other water parameters translate from temp..

    here is the basic equation

    increased temp = reduction of O2 = increase of CO2 = Depression of ph

    now the resting i am more interested in is Calcium, Alk, Magnesium, Iodine, Iron, Silicate, Phosphate, to name a few.

    while all chemistry should remain within check or in an aceptable varience..

    some are more lethal/critical than others..
     
  12. clinton stanford

    clinton stanford

    Joined:
    11 Mar 2009
    Posts:
    2,210
    Likes Received:
    4
    Location:
    East London
    surely with the technoligy we have today they could have come up with a electronic device where you could test all params.like a refractometer:whistling:
     
  13. leslie hempel

    leslie hempel Thread Starter Moderator MASA Contributor

    Joined:
    7 May 2007
    Posts:
    14,546
    Likes Received:
    287
    Location:
    Gonubie East London
    point taken, and a very interesting and a very valid point..tablets should also be handled with gloves on etc because the PH can effect the chemical. i have seen this happen with sweaty hands and the test strips (our LFS owner handles the test strips and cuts them in half to get more cash from testing but in the process contaminates the test strips)


    i am also pro the electronic/digital probe route for testing. cant really see much that can do wrong other than not changing the probe on regular maintenance intervals or allowing it to get knocked.

    expense is a concern but well worth it for accurate testing...
     
  14. leslie hempel

    leslie hempel Thread Starter Moderator MASA Contributor

    Joined:
    7 May 2007
    Posts:
    14,546
    Likes Received:
    287
    Location:
    Gonubie East London
    always nice to have, but costly. and still may not be able to point out the exact problem causing the inacuracy..

    my question comes from when i went to hospital last sunday... they tested my blood sugar level and it read 10.9... which is high.. i am supposed to be in the region of 5 or 6.. i was immediatley told i was diabetic but when another more experienced nurse came to give a second opinion she said it was not necessarly the cause and it was more than likley a reflection of some sort of incftion in my system.

    i have been tested since and the test read 6.5 which is better and i had eaten something on the drive in (you are not supposed to eat anything for a period prior to being tested for sugar)

    so if they getting it wrong on humans what chances do our inhabitants have :tt2:
     
  15. archiecrain

    archiecrain

    Joined:
    23 Jun 2010
    Posts:
    1,391
    Likes Received:
    59
    Location:
    Fourways

    I was always under the impression that the tablet tests are inferior to the drop and powder test's....?
     
  16. leslie hempel

    leslie hempel Thread Starter Moderator MASA Contributor

    Joined:
    7 May 2007
    Posts:
    14,546
    Likes Received:
    287
    Location:
    Gonubie East London
    perhaps so, but what dallas is trying to illustrate here is the consistency of measurements of drops added vs tablets....

    the drop size may vary or an extra one added by mistake, if the tablet is in a sound condition with no crakcs or pieces broken off of it it should be consistent time after time...

    but still this is completley debatable...
     
  17. 2balive

    2balive

    Joined:
    6 May 2007
    Posts:
    2,179
    Likes Received:
    39
    Location:
    Camps Bay, Cape Town
    Temperature correction for salinity refractometer

    Only read my refractometer's manual tonight and realized that it does not have automatic tempature compensation and is set for 20deg.

    Is the difference meaningful and where can I get a compensation factor and/or tables?
     
Recent Posts

Loading...
Similar Threads - Understanding Testing Forum Date
Understanding Old Tank Syndrome (by me) General Discussions and Advice 17 Mar 2016
Understanding the info on the salt bucket Beginner Discussions 13 Oct 2014
Understanding parameters Beginner Discussions 22 Apr 2014
Understanding mixing salt poll General Discussions and Advice 11 Mar 2014
Understanding Magnesium,Alkalinity,PH and General Hardness Water Parameters and Additives 28 Jan 2012
Understanding RGB LED . Mythbusting Lighting 30 Oct 2011
Understanding LED lighting for a reef Lighting 20 Oct 2011