Re: [APD] Estimative Index for CO Dosing - Bah!

[Jerry Baker <jerry at bakerweb_biz>]

Vaughn Hopkins wrote:
> How can we tell that we have 20 ppm or 30 ppm or whatever CO2 
> concentration, when the PH/KH/CO2 table isn't accurate due to other 
> water parameters?  The advice to increase CO2 until the fish don't like 
> it is just a way to find out how much we have, when no other way is 
> available.   Of course if we had good test equipment available to 
> accurately measure all water parameters, including CO2, we could use 
> them and optimize everything.

You can add a correction factor to your water by measuring its value 
after being equalized with the atmosphere. We know that water at room 
temperature will equalize with CO2 in the atmosphere at around 4.6 mg/L 
(if I'm doing Henry's Law correctly). That will allow you to correct 
your KH test.

For instance, say your KH test says your water is 5 degrees, but when 
you let your water sit out overnight the pH is 7.3. That means that your 
KH is really about 3 degrees and 2 of those degrees reported by your 
test kit are sources of alkalinity other than carbonates. For figuring 
CO2, just use 3 from then on (until you change something).

-- 
Jerry Baker
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