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Re CO2

Steve, my verbage was poor and I certainly agree with your analysis 
below. I am a proponent of using CO2 and undoubtedly that will have 
an effect on the PH level. What I meant to say was that I have seen 
instances of people using PH 8.2 tapwater and then using a CO2 
controller to maintain a level 5 PH. This in my opinion is not safe. 
And for the record, I have seen fish go into PH shock even after 
following proper temperature/other acclimation procedures.

I suppose what I should say is that I recommend people choose a PH 
range that is appropriate for the fish and plants. Then decide what 
carbonate hardness you want so that you have a desirable level of CO2 
in the water. For example, in my example above where the individual 
used PH 8.2 water, the carbonate hardness was close to 17. Keeping 
the carbonate hardness constant and adding CO2 to lower the PH to 
even 6 could prove quite dangerous to fish.

Steve Dixon wrote:

>Let's look at the implications of Julius' first sentence.  The equilibrium
>level of dissolved CO2 in a water column exposed to air is fairly low,
>around 2 - 3 ppm CO2.  This is well-below the optimum level for growing many
>species of aquatic plants.  We might see a general increase in plant
>vitality at say, 10 - 15 ppm and a variety of plants seem to prefer 20 - 25
>ppm CO2.  If we are not to artificially lower the pH by adding CO2, then we
>must not add ANY CO2 to the water column.  Because as we know, adding CO2
>will in fact lower the pH.  I wonder if Julius is recommending not adding
>any CO2 to our tanks to avoid potential fluctuation in pH or perhaps
>something else, such as not adding much CO2 to the water column.

Julius Odian
Menlo Park, CA

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