Fishkeeping - Just Checking

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"boooger" wrote in message m...
In your hypothetical example if the test kit only reduces
50% of the nitrate than the math still works.

Only if you KNOW it is 50%. But you dont know that!
It is not given on the carton box with the test...
It is not published on the manufacturer website.
How will you know ? Will you calibrate yourself ?

Assume I have 30 ppm nitrate and 10 ppm nitrite and the test kit reduces 50%
of the nitrate. Now I will have 15 ppm + 10 ppm nitrite. The test kit
will give a value of 35 ppm nitrate (15 ppm + 2*10 ppm).

Now measure nitrite and multiply by a factor of 2 and you get 20 ppm
nitrite.

(15 ppm +2*10 ppm) - 20 ppm = 15 ppm nitrate.

Get it?

Where do you get the factor of 2 ?
Why not factor of 3 or 5 ? Get it ?

I need a proof which shows the basic assumption is true.
Show me proof for more than 95% of nitrates being reduced
in aquarium grade test kits available in aquarium stores.

Show me proof that it doesn't.

Your claim is that you can do simple math to get nitrates
using aquarium tests, even while nitrites are present...
Your simple math works only when you set asumption, but you
cannot prove your assumption to be true. This does not hold!

Note - we do not use cooper-cadmium reducing towers...
We just dump a little cadmium dust in the vial and shake
the vial. Who knows how much nitrates gets reduced!

I am referring to STORE bought test kits.
None that I have seen use cadmium dust.

What do you think they use ? Yes, they do use unoxidated
metal - cadmium or zinc - usually delivered in suspension...
That is why you are asked to shake the bottle # 2 for 30
seconds (to lift cadmium dust from the bottom of the bottle)
before you use it.

My Aquarium Pharmaceuticals test is bright yellow when
there are no nitrates, and goes through orange to dark
red-orange at high nitrates. Reading done at the time given
in the user manual (5 minutes) differs from the reading
done after 1/2 hour... Based on this observation I conclude that during
standard 5 minutes time not all nitrates get reduced and you cannot
simply subtract one value from another or not Similar situation
might be with other tests - that is why
manufacturer is stating that reading should be done at
the certain time, not sooner, not later because this is
how the color scale got calibrated.

No comments to this, Maestro ?

"Pszemol" wrote in message
...
"boooger" wrote in message
m...
In your hypothetical example if the test kit only reduces
50% of the nitrate than the math still works.

Only if you KNOW it is 50%. But you dont know that!
It is not given on the carton box with the test...
It is not published on the manufacturer website.
How will you know ? Will you calibrate yourself ?

How do you know it's not 95% or 98% or 100% ?

Assume I have 30 ppm nitrate and 10 ppm nitrite and the test kit reduces
50% of the nitrate. Now I will have 15 ppm + 10 ppm nitrite. The
test kit will give a value of 35 ppm nitrate (15 ppm + 2*10 ppm).

Now measure nitrite and multiply by a factor of 2 and you get 20 ppm
nitrite.

(15 ppm +2*10 ppm) - 20 ppm = 15 ppm nitrate.

Get it?

Where do you get the factor of 2 ?
Why not factor of 3 or 5 ? Get it ?

Factor of 2 because in your example you state only 50% reduced. Therefore
you have to multiply your nitrite test results by a factor of 2 so they
equal the calibration scale in the nitrate test.

I need a proof which shows the basic assumption is true.
Show me proof for more than 95% of nitrates being reduced
in aquarium grade test kits available in aquarium stores.

Show me proof that it doesn't.

Your claim is that you can do simple math to get nitrates
using aquarium tests, even while nitrites are present...
Your simple math works only when you set asumption, but you
cannot prove your assumption to be true. This does not hold!

You can not prove your assumption that it does not hold.

Note - we do not use cooper-cadmium reducing towers...
We just dump a little cadmium dust in the vial and shake
the vial. Who knows how much nitrates gets reduced!

I am referring to STORE bought test kits.
None that I have seen use cadmium dust.

What do you think they use ? Yes, they do use unoxidated
metal - cadmium or zinc - usually delivered in suspension...
That is why you are asked to shake the bottle # 2 for 30
seconds (to lift cadmium dust from the bottom of the bottle)
before you use it.

I misunderstood you. I usually don't refer to particles in a suspension as
"dust".

My Aquarium Pharmaceuticals test is bright yellow when
there are no nitrates, and goes through orange to dark
red-orange at high nitrates. Reading done at the time given
in the user manual (5 minutes) differs from the reading
done after 1/2 hour... Based on this observation I conclude that during
standard 5 minutes time not all nitrates get reduced

Based on this observation YOU assume. Your conclusion is an assumption.

"boooger" wrote in message m...
"Pszemol" wrote in message
...
"boooger" wrote in message
m...
In your hypothetical example if the test kit only reduces
50% of the nitrate than the math still works.

Only if you KNOW it is 50%. But you dont know that!
It is not given on the carton box with the test...
It is not published on the manufacturer website.
How will you know ? Will you calibrate yourself ?

How do you know it's not 95% or 98% or 100% ?

I do not know - you do not know either. You can only guess.
If you can guess 95%, I can guess 20%, 50%, 75% - anything else.
It could be even worse than that - it could be that Tetra test
reduces only 20%, AP test reduces 45% and HACH test 70%...
You have NO IDEA! :-) These tests are for nitrates only, so
they do not provide any information needed in your "math".
I asked you for the source of this number and you cannot provide it.

Assume I have 30 ppm nitrate and 10 ppm nitrite and the test kit reduces
50% of the nitrate. Now I will have 15 ppm + 10 ppm nitrite. The
test kit will give a value of 35 ppm nitrate (15 ppm + 2*10 ppm).

Now measure nitrite and multiply by a factor of 2 and you get 20 ppm
nitrite.

(15 ppm +2*10 ppm) - 20 ppm = 15 ppm nitrate.

Get it?

Where do you get the factor of 2 ?
Why not factor of 3 or 5 ? Get it ?

Factor of 2 because in your example you state only 50% reduced. Therefore
you have to multiply your nitrite test results by a factor of 2 so they
equal the calibration scale in the nitrate test.

BUT YOU, THE USER OF THE TEST, DO NOT KNOW WHAT THE FACTOR IS.
Get it ?

I need a proof which shows the basic assumption is true.
Show me proof for more than 95% of nitrates being reduced
in aquarium grade test kits available in aquarium stores.

Show me proof that it doesn't.

Your claim is that you can do simple math to get nitrates
using aquarium tests, even while nitrites are present...
Your simple math works only when you set asumption, but you
cannot prove your assumption to be true. This does not hold!

You can not prove your assumption that it does not hold.

You cannot give me the source for your 95% "guess".
This is the proof that your story does not hold.

Note - we do not use cooper-cadmium reducing towers...
We just dump a little cadmium dust in the vial and shake
the vial. Who knows how much nitrates gets reduced!

I am referring to STORE bought test kits.
None that I have seen use cadmium dust.

What do you think they use ? Yes, they do use unoxidated
metal - cadmium or zinc - usually delivered in suspension...
That is why you are asked to shake the bottle # 2 for 30
seconds (to lift cadmium dust from the bottom of the bottle)
before you use it.

I misunderstood you.
I usually don't refer to particles in a suspension as "dust".

That's ok... :-)

My Aquarium Pharmaceuticals test is bright yellow when
there are no nitrates, and goes through orange to dark
red-orange at high nitrates. Reading done at the time given
in the user manual (5 minutes) differs from the reading
done after 1/2 hour... Based on this observation I conclude that during
standard 5 minutes time not all nitrates get reduced

Based on this observation YOU assume. Your conclusion is an assumption.

At least I have my observations to back up my assumptions.
You have NOTHING to back up your 95%! You just guessing.
You just pulled this number who know where from...
It is called wishful thinking, my friendly Ant!

So do your homework and prove it is over 95%.
Back up this statement with some REAL data...

How do you know it's not 95% or 98% or 100% ?

I do not know - you do not know either.

You are correct, YOU DON'T KNOW. The thing is, I DO KNOW.

Don't want to believe me? I don't care Grasshopper!

You want to dispute me and I am stuck with the burden of providing "proof"
?

It doesn't work this way. YOU are disputing me, therefore YOU provide proof
that supports YOUR claim.

GOOD LUCK Grasshopper!

"boooger" wrote in message m...
How do you know it's not 95% or 98% or 100% ?

I do not know - you do not know either.

You are correct, YOU DON'T KNOW. The thing is, I DO KNOW.

No, you do not. You only guess. Wishfull thinking.

Don't want to believe me? I don't care Grasshopper!

You want to dispute me and I am stuck with the burden
of providing "proof" ?

It doesn't work this way.

Yes, it does - you are the teacher - prove you KNOW it.

YOU are disputing me, therefore YOU provide proof
that supports YOUR claim.

GOOD LUCK Grasshopper!

You are funny... you pulled the number out of your ass
and you want me to believe you - why should I ? I am not!
You make a claim - prove it. But you cannot prove your statement.
Your statement is Booooooooogggguuuuss.

Good teacher could point me to the data for the statement.
You cannot - this proves again you are not a teacher :-)))

I do not know what exact percentage gets reduced -
I can see what is important: this is not even close to 95%
because you would not see the color change after longer time...

So here it is - a prove that your statement is BOGUS!

"Wayne Sallee" wrote in message nk.net...
I think that only happens with test kits that test
nitrogen nitrate, instead of testing NO3.

For example, Marine Enterprise NO3 and Tetra NO3 will test
accurately.

I do not think it makes any difference
what is the scale calibrated to.
They all will have only fraction of nitrates reduced
to nitrites and nitrites present in the sample will
interfere with the proper reading of nitrates...

Nitrites in the sample aquarium water just make
nitrate test inacurate enough to not do it at all.

"Pszemol" wrote in
:

"Wayne Sallee" wrote in message
nk.net...
I think that only happens with test kits that test
nitrogen nitrate, instead of testing NO3.

For example, Marine Enterprise NO3 and Tetra NO3 will test
accurately.

I do not think it makes any difference
what is the scale calibrated to.
They all will have only fraction of nitrates reduced
to nitrites

The reduction reaction of cadmium or zinc with nitrate is pretty
efficient. Given good contact and agitation with fresh metal, about 95%
reduction of nitrate to nitrite can be expected.

http://lachatinstruments.com/downloa...ALNReprint.pdf

That link references column and cup methods of automated nitrate
testing, but the principle of the reduction reaction is the same.

If you can lay your hands on ASTM test methods, the number for Nitrate-
nitrite testing in water is ASTM D 3867-04, which corroborates the above
reduction efficiency. Given that ASTM methods are sold for profit,
there isn't a link I can point you to for the test method, other than
the one which sells the pdf for 48 bucks;

http://www.astm.org/cgi-
bin/SoftCart.exe/DATABASE.CART/REDLINE_PAGES/D3867.htm?
L+mystore+hbqn6245

There might be a book containing these methods in your local library...

Regards,
DaveZ
Atom Weaver

"atomweaver" wrote in message ...
The reduction reaction of cadmium or zinc with nitrate is pretty
efficient. Given good contact and agitation with fresh metal, about 95%
reduction of nitrate to nitrite can be expected.

http://lachatinstruments.com/downloa...ALNReprint.pdf

That link references column and cup methods of automated nitrate
testing, but the principle of the reduction reaction is the same.

I am not arguing effectiveness of the method in the lab...

I am talking exclusively about aquarium grade test kits here.

The principle might be identical, but resulting process might be not
as efficient when done in a test tube as when it is done in the lab,
in a properly designed reducing column... And that is the problem here.

"Pszemol" wrote in
:

"atomweaver" wrote in message
...
The reduction reaction of cadmium or zinc with nitrate is pretty
efficient. Given good contact and agitation with fresh metal, about
95% reduction of nitrate to nitrite can be expected.

http://lachatinstruments.com/downloa...ALNReprint.pdf

That link references column and cup methods of automated nitrate
testing, but the principle of the reduction reaction is the same.

I am not arguing effectiveness of the method in the lab...

I am talking exclusively about aquarium grade test kits here.

The principle might be identical, but resulting process might be not
as efficient when done in a test tube as when it is done in the lab,
in a properly designed reducing column... And that is the problem
here.

Meh. Get cadmium or zinc in contact with nitrates, and you're going
to get a good conversion of nitrite. All the "powder plus dropper" test
kits I've used have a _large_ excess of metal vs. anticiapted nitrates
in the measured range of 0-100 ppm Nitrate.

Check out this math; If you're testing 1 mL of water with 10 mg/L
Nitrate, it contains 0,01 mg of Nitrate (=0,00001 g). In most test
kits, you're adding about 10,000 times that amount (0,1 g) of reducing
agent, by weight. No, I don't think that much, if any, nitrate will
remain unreduced, regardless of the operator. I get your general drift
(people are inept, test kits can have old, unreliable contents), but
follow the instructions with fresh reagents, and the home kits give
accurate enough numbers. That's not to say that home kits aren't
problematic... just that failure to reduce nitrates to nitrites isn't a
likely scenario. More likely is for test error to come in the form of
(mis)reading the test's end-result (cruddy colorimetric comparison
charts, or some such).

An aside;
This paper investigated how high phosphate levels in samples evaluated
with the cadmium test can impact your nitrate values by interfering with
the reduction reaction, giving you readings to the tune of up to 25% low
nitrate values.

http://aslo.org/lo/toc/vol_25/issue_4/0758.pdf

Something to remember...

I also read somewhere there's an enzyme reduction method out there which
is highly selective (none of the common interferences, 99%
reduction)... gotta love those little bugs :-)

Regards,
DaveZ
Atom Weaver