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Re: [APD] CO2 drop checker -- Or -- The gas is always greener in the other guy's tester



Well, if your aquarium water has something throwing off the reading, you can take a H measurement then take some aquarium water and let is sit over night so that it is basically depleted of CO2 and then check the pH again, and use that one time calc to make an adjustment.

sh
 
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----- Original Message ----
From: Vaughn Hopkins <hoppycalif at yahoo_com>
To: aquatic plants digest <aquatic-plants at actwin_com>
Sent: Tuesday, October 17, 2006 2:48:38 PM
Subject: Re: [APD] CO2 drop checker -- Or -- The gas is always greener in the other guy's tester


On Oct 17, 2006, at 11:03 AM, S. Hieber wrote:

> Hmm, if there are other acids, they will reduce the KH by reacting  
> with the carbonates and the pH/KH/CO2 table won't be affected at  
> all. I don't think other alkalinity factors  (magnesium) will  
> create a significant problem eithe, which is as it should be. There  
> are some other kinds of compounds that one can purposely add that  
> might throw things off by goofing up the tests themselve, but  
> whether, in general, the effect is significantly beyond the margin  
> of error of pH and KH tests, or the pH tester you're talking, about  
> is another matter. I think it's actually unlikley to make a diff  
> that matters to an aquatic gardening. Is the tank running at about  
> 5pm higher or lower than tests indicate? Won't matter worth a damn  
> in most cases. In any event, the fine-tuning prescription would be,  
> if the plants show too little CO2, slightly increase the CO2.  
> Reduce it slightly if the animates seem stressed.
>
> What I mean is, these tests and indicators, they're just fingers in  
> the wind -- the goal, the objective, is the growth of the plants  
> and health of the fish, so that's always the final arbiter of  
> action, the counselor of conditions.
>
> For myself, I'd just as soon have an electronic pH tester as a  
> chemical kit. But those that can't afford them, or don't want to,  
> and can use them, they're certainly adequate if one watches the  
> plants.
>
> This in-the-tank device certainly would work too, but I doubt it  
> has any substantial efficacy beyond other methods. My biggest  
> complaint is that it's another device in the tank and maybe that it  
> reports changes in CO2 levels very slowly -- small complaints all  
> and ones that not all would have.
>
> sh
>
>
It should be obvious that I am not a chemist.  But, for some reason  
most of us who do conventional tests for CO2 in our tank come up with  
absurdly high numbers or we come up with reasonable numbers and have  
obvious CO2 deficiencies.  I used to consistently show 70 to 120 ppm  
of CO2 doing those tests, and I still had BBA popping out.  So, there  
is something basically wrong with that method for testing for CO2.

Once we become adept at reading the plants and fish, a CO2 test is  
superfluous.  But, we relative newbies can't do that well.  It is for  
us that a better method for measuring CO2 is valuable.

If you have some valuable fish in your tank (I don't) you will be  
very reluctant to raise your CO2 up above the 30 ppm you measure by  
measuring KH and pH.  Even if you find the courage to do so, you may  
raise it to 45 ppm using the same method - see a couple of fish which  
seem to be panting, and immediately drop it again, believing that you  
have as much CO2 as you can use.  Then you just live with low CO2  
problems forever, always wondering why Tom and others keep saying  
"raise your CO2 concentration".  I don't like to see that if there is  
an easy way to avoid it.

Vaughn H.

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