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Re: CO2 test kit

> From: "Arturo Batista" <artbatista at artbatista_com>
> Subject: CO2 Test kit
> When I used my test kit for the first time, I simply could not get a reading
> for CO2. The way my test kit works is you get a sample (10 ML) of water, add
> 5 drops of reagent A, which makes your water sample a certain color,

	An acid/base indicator.

> then
> you add Reagent B

	Very dilute sodium hydroxide solution.

> 1 drop at a time. When the water color matches the "END"
> color in the chart you take the number of Reagent B drops, multiply by 2 and
> thats's your CO2 PPM. I went all the way to 40 drops of reagent B and my
> water sample never reached the "End" Color, it never even changed. So I have
> 3 possibilities that I can think of:
> A:- My test kit is defective

	Very probably

> B:- My CO2 concentration is extremely high (over 80 PPM)

	No way.

> C:- I dont' know what the hell I am doing.

	Even if you don't, following the instructions should work!!!  :)

> So the question is: Is my CO2 really that high?

> I called Big Al's from whom I bougth the test kit (Plant Care Mini-Lab Test
> Kit from Red Sea) and they were very helpful.  Since my Reagent B cap was
> not on straight when I first received the kit (manufacturing problem I
> think, cap was sealed but it was threaded crooked on bottle), they think
> that maybe the solution was exposed to the air and has become inert. 

	It absorbs CO2 (surprise) and becomes inert quite easily.

> are shipping me a replacement bottle of "B",

	Good idea.  I have commented on this test before.  It's inherently
pretty unsatisfactory, because the "B" reagent must be so dilute.  I would
prefer the pH/KH/table route to get the CO2 concentration.  Neither the
indicator for the pH test nor the reagents for the KH test will deteriorate
significantly.  For the CO2 test kit, it's the quality of the "B" _bottle_
that counts - it has to keep the CO2 out.

Paul Sears        Ottawa, Canada