Understanding Testing

leslie hempel

leslie hempel

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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..
 
i am reffering to testing using reagents and not electronic testing but for the sake of interest perhaps these should be included aswell?
 
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.
 
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.
 
lIghty said:
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.
Click to expand...


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......
 
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?
 
lIghty said:
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.
Click to expand...


so if your water has to be semi accurate to get a reading what are we testing for:tt2:
 
robertkukla said:
tagging along i am very interested in how the one can affect the other especially the calcium scenario
Click to expand...

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..
 
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:
 
dallasg said:
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?
Click to expand...

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...
 
clinton stanford said:
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:
Click to expand...

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:
 
dallasg said:
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?
Click to expand...


I was always under the impression that the tablet tests are inferior to the drop and powder test's....?
 
archiecrain said:
I was always under the impression that the tablet tests are inferior to the drop and powder test's....?
Click to expand...

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...
 
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