Re: [APD] CO2 drop checker

[Vaughn Hopkins <hoppycalif at yahoo_com>]

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.

Vaughn H.

On Oct 17, 2006, at 6:06 AM, S. Hieber wrote:

> The diff between 30ppm and 65ppm could be total and permanent loss  
> of animation of the animate inhabitants. For those who weakly  
> perceive color diffs in the yell-blue-green range. the best bet  
> might be to save up for an inexpensive electronic pH meter. One  
> portable meter will work for a great many aquaria.
>
> sh
>
>
> ----- Original Message ----
> From: Vaughn Hopkins <hoppycalif at yahoo_com>
> To: aquatic plants digest <aquatic-plants at actwin_com>
> Sent: Monday, October 16, 2006 9:15:14 PM
> Subject: Re: [APD] CO2 drop checker
>
>
> Jerry,
> If you can see a clear difference between yellow, orange, and red,
> this can be used with a different indicator solution.  Phenol Red
> would work fine for this purpose, and ebay now has someone selling
> Phenol Red for less than $20 for ten lifetimes supply.  This would
> require setting the KH of the water in the bulb to 20 degrees.  Then
> orange would indicate 30 ppm, yellow orange would be about 65 ppm,
> and red orange would be about 15 ppm.  I haven't tried it, of course,
> but theoretically it would work, if the differences in color were
> easy enough to see.  I haven't found any other indicator that would
> work, that isn't yellow/green/blue.  Why don't you try this??
>
> Vaughn H.
> On Oct 16, 2006, at 1:57 PM, Jerry Baker wrote:
>
>>
>>
>> Just curious to hear from anyone who actually has this. Is the green
>> color a dark green, or a bright green (i.e., is there a noticeable
>> contrast difference)? I ask because the difference between bright
>> green
>> and yellow is non-existent for about 10% of us males. Thanks.
>>
>> -- 
>> Jerry Baker
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