Re: [APD] CO2 drop checker

[Dennis Dietz <dennisdietz at verizon_net>]

Thats actually an interesting idea.  The probe is contained in a 
specifically buffered solution.  The drop checker method means that the 
pH of that solution is based entirely on how much CO2 is dissociating 
from the aquarium water.  You now have accurate representation of CO2 in 
the tank, based on kH/pH tables but it is completely unaffected by the 
tank water itself.

BTW, a cheap tester can be made by heating and bending the glass test 
tube that comes with the AP pH test kit.  You also get your Phenol blue 
with the little kit. so grab your benzomatic torch and a pair of gloves:)

Dennis

Vaughn Hopkins wrote:
> Nothing requires the "drop checker" to be a tiny little thing.  So,  
> it wouldn't be hard to design one that was big enough and had a  
> sealed port at the top for a pH probe.  It wouldn't need to be  
> transparent, so a plastic would work fine.  Sit down at the drafting  
> board and see what you can come up with!
>
> Vaughn H .
>
> On Oct 17, 2006, at 10:44 AM, Jerry Baker wrote:
>
>   
>> Vaughn Hopkins wrote:
>>     
>>> The problem is that measuring the pH and KH of the tank water doesn't
>>> tell you how much CO2 is in the tank water.  That water almost always
>>> contains some other sources of alkalinity and acidity besides CO2, so
>>> the equation relating pH/KH/CO2 isn't applicable.  The "drop checker"
>>> lets us get around that problem by using distilled water with just
>>> sodium bicarbonate in it as a test solution.   I have no idea how
>>> well the Phenol Red would work in this device, or how easy it is to
>>> discriminate between orange and yellow orange or reddish orange.
>>> But, trying it out wouldn't be terribly expensive.  I suspect that
>>> the "high range" pH test kits may use Phenol Red and would be a good
>>> thing to experiment with too.
>>>       
>> What might be *really* interesting to those of us who appreciate
>> precision for precision's sake is figuring out a way to get a pH probe
>> into that distilled water.
>>
>>
>> -- 
>> Jerry Baker
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>>     
>
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>   

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