Acuracy of color tests in our trade...

[Pszemol]

I am curious if anybody was thinking about it,
what is the accuracy of measuring Ca++, Mg++,
Strontium, alkalinity, phosphates, ammonia,
nitrites, nitrates - not mentioning pH tests?
I was looking for this info on the boxes and
literature which comes with the tests and I
have found references to "precision" of 5mmg/l
for Seachem Calcium test and precision of 0.5
mg/l for Seachem Strontium test I have...
Anybody knows the average accuracy one can
determine calcium/magnesium levels in the tank?

I know the accuracy of the tests used in reef
hobby is "good enough", people use it and are
doing good, but for the better interpretation
of results I got from testing I would like to
know what is the accuracy of the measurement
of - let's say - Calcium level 500mg/l
In terms of +/-(X mg/l) or percentage of the value.
Would it be 1%? 5%? Or maybe +/- 20%?

[Boomer]

Sr is another issue. The only ones that make kits for it are aquarium companies. They seem
to be OK. Ca and Mg, yes you ca get a HACH digital Titrator, like the one I just gave to
Randy on our Chem. Forum. It can measure them down to 0.1 mg / l as CaCO3, which converts
to 0.1 x 0.44 =.044 mg / l .Ca and .1 x .29 = .029 mg/ l Mg. This is not precession but
the smallest increment or precession. Allot of this so called precession or accuracy is
based on you and your eyes :-)

HAC-DT cat. number 20639-00 around $ 200

www.hach.com


5 mg/l Ca is good enough as is =5 mg / l Mg. Sr. is only around 8 mg / l in NSW, so .5 is
good enough.

I just went through a number of my test kit catalogs for you and none of them give
accuracy, except for meters, just smallest unit of measurement. :-(
--
Boomer

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"Pszemol" > wrote in message ...
:I am curious if anybody was thinking about it,
: what is the accuracy of measuring Ca++, Mg++,
: Strontium, alkalinity, phosphates, ammonia,
: nitrites, nitrates - not mentioning pH tests?
: I was looking for this info on the boxes and
: literature which comes with the tests and I
: have found references to "precision" of 5mmg/l
: for Seachem Calcium test and precision of 0.5
: mg/l for Seachem Strontium test I have...
: Anybody knows the average accuracy one can
: determine calcium/magnesium levels in the tank?
:
: I know the accuracy of the tests used in reef
: hobby is "good enough", people use it and are
: doing good, but for the better interpretation
: of results I got from testing I would like to
: know what is the accuracy of the measurement
: of - let's say - Calcium level 500mg/l
: In terms of +/-(X mg/l) or percentage of the value.
: Would it be 1%? 5%? Or maybe +/- 20%?

[Pszemol]

Thanks Boomer... I understand color intensity tests are not
accurate since we all see colors little different, for
example I heard that women read colors better than men...
Not sure if this is true, but it would show how relative
would the accuracy be for these kinds of tests.

But Seachem Ca, Mg tests are based on titration, so the
color change is quite sharp and relatively easier to notice.
One could expect these tests are more accurate than color
intensity tests like ones for ammonia, nitrates, etc.

How much trust can we really put into such readings??? 5%? 1%?
If you, Boomer, titrated with this 1cc syringe to Ca++ level 500.0mg/l
with a Seachem color test - how confident would you be to the results?
How much variation +/- would you estimate average reefer can get
from these kind of titration tests? Would it be really +/-5mg/l Ca?
Is it practical or rather more theoretical value?
Should we really treat this "precision" statement rather as
a resolution capability? Same thing as with discussion about swing
arm hydrometers compared to more accurate to be refractometers?

"Boomer" > wrote in message ...
> Sr is another issue. The only ones that make kits for it are aquarium companies. They seem
> to be OK. Ca and Mg, yes you ca get a HACH digital Titrator, like the one I just gave to
> Randy on our Chem. Forum. It can measure them down to 0.1 mg / l as CaCO3, which converts
> to 0.1 x 0.44 =.044 mg / l .Ca and .1 x .29 = .029 mg/ l Mg. This is not precession but
> the smallest increment or precession. Allot of this so called precession or accuracy is
> based on you and your eyes :-)
>
> HAC-DT cat. number 20639-00 around $ 200
>
> www.hach.com
>
>
> 5 mg/l Ca is good enough as is =5 mg / l Mg. Sr. is only around 8 mg / l in NSW, so .5 is
> good enough.
>
> I just went through a number of my test kit catalogs for you and none of them give
> accuracy, except for meters, just smallest unit of measurement. :-(
> --
> Boomer
>
> Want to talk chemistry ? The Reef Chemistry Forum
> http://www.reefcentral.com/vbulletin/index.php
>
> Want to See More ?
> Please Join Our Growing Membership
> www.coralrealm.com
>
> If You See Me Running You Better Catch-Up
> "Pszemol" > wrote in message ...
> :I am curious if anybody was thinking about it,
> : what is the accuracy of measuring Ca++, Mg++,
> : Strontium, alkalinity, phosphates, ammonia,
> : nitrites, nitrates - not mentioning pH tests?
> : I was looking for this info on the boxes and
> : literature which comes with the tests and I
> : have found references to "precision" of 5mmg/l
> : for Seachem Calcium test and precision of 0.5
> : mg/l for Seachem Strontium test I have...
> : Anybody knows the average accuracy one can
> : determine calcium/magnesium levels in the tank?
> :
> : I know the accuracy of the tests used in reef
> : hobby is "good enough", people use it and are
> : doing good, but for the better interpretation
> : of results I got from testing I would like to
> : know what is the accuracy of the measurement
> : of - let's say - Calcium level 500mg/l
> : In terms of +/-(X mg/l) or percentage of the value.
> : Would it be 1%? 5%? Or maybe +/- 20%?
>
>

[Steve \Srfmon\]

I usually break out the test kits every 3 months or so. I guess I'm just
lazy. But once you get your Ca Reactor dialed in & levels are
steady.......things are good!
Besides I always thought that the appearance of your livestock can tell
you way more than a test kit.
"Pszemol" > wrote in message
...
> I am curious if anybody was thinking about it,
> what is the accuracy of measuring Ca++, Mg++,
> Strontium, alkalinity, phosphates, ammonia,
> nitrites, nitrates - not mentioning pH tests?
> I was looking for this info on the boxes and
> literature which comes with the tests and I
> have found references to "precision" of 5mmg/l
> for Seachem Calcium test and precision of 0.5
> mg/l for Seachem Strontium test I have...
> Anybody knows the average accuracy one can
> determine calcium/magnesium levels in the tank?
>
> I know the accuracy of the tests used in reef
> hobby is "good enough", people use it and are
> doing good, but for the better interpretation
> of results I got from testing I would like to
> know what is the accuracy of the measurement
> of - let's say - Calcium level 500mg/l
> In terms of +/-(X mg/l) or percentage of the value.
> Would it be 1%? 5%? Or maybe +/- 20%?

[Boomer]

"I understand color intensity tests are not
accurate since we all see colors little different, for
example I heard that women read colors better than men...
Not sure if this is true, but it would show how relative
would the accuracy be for these kinds of tests."

Yes, that is true. Some people often just hold it up to the wrong light source.

"But Seachem Ca, Mg tests are based on titration, so the
color change is quite sharp and relatively easier to notice.
One could expect these tests are more accurate than color
intensity tests like ones for ammonia, nitrates, etc."

Yes, that is why those types work better for the most part but people have problems there
also on some titrations

"How much trust can we really put into such readings??? 5%? 1%?"

It depends on the kit and often who makes it. That is why we recommend HACH and La Mote
for example or Salifert or the basic SeaTest (NO3, NO2, Cu, pH and NH3, we have issues
with their Ca and Alk)


"If you, Boomer, titrated with this 1cc syringe to Ca++ level 500.0mg/l
with a Seachem color test - how confident would you be to the results?"

Titration is a std means. Most kits or titrations kits follow a guide line set down in

"Standard Method for the Examination of Water and Wastewater"

This book will give you the exact procedures that are accepted. With this book you can
make your own test kits

"How much variation +/- would you estimate average reefer can get
from these kind of titration tests? Would it be really +/-5mg/l Ca?"

This something Randy has been doing, so be patient.. You need to check the kit against an
ICP. He is working on one now for pH test kits ( not ICP for pH) in this hobby and their
accuracy. He did one the SeaChem Borate kit, which appeared in our on-line magazine. It
did not test out to good and it was a titration procedure. The SeaTest kit comes with a
std to compare with. I think it is 500 mg / l Ca++. HACH and La Motte also make std to
compare with. We don't know for sure how accurate some of them are, as some use unaccepted
methods, which does not mean they are less accurate. Some kits have a reputation of giving
poor results, for example RedSea Ak. There will always be a kit here and there where the
reagents are bad. Salifert had allot of problems with their O2 kit always giving the same
O2 levels. I don't test things anymore and really couldn't if I wanted, I sent Randy all
my stuff.


"Is it practical or rather more theoretical value?"

No, it is practical. We do need to know how accurate these kits are.

Should we really treat this "precision" statement rather as
a resolution capability? Same thing as with discussion about swing
arm hydrometers compared to more accurate to be refractometers?

--
Boomer

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Please Join Our Growing Membership
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[Richard Reynolds]

> Besides I always thought that the appearance of your livestock can tell
> you way more than a test kit.

thats true until you have 3000 clowns in a 55 :D
or are talking about getting the maximum growth out of something that grows slowly. by the
time you notice it hasnt grown enough your levels may be very far off. and thatll cut into
profit :D

--
Richard Reynolds