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Re: Minor technical corrections

>Date: Sat, 16 Sep 2000 13:47:49 -0700
>From: Wright Huntley <huntley1 at home_com>
>Subject: pH hogwash?
>4 ) pH is a useful thing to measure, along with alkalinity (unfortunately
>confused with hardness by calling it "carbonate hardness") primarily to use
>the CO2 concentration equations or charts to set the CO2 level for proper
>plant nutrition.

Just to be perfectly clear: The pH/CO2 charts are based on the measure of the 
carbonate ions present in the water, often called carbonate hardness or KH. KH 
can NOT be measured directly, so an alkalinity test is usually substituted. If 
carbonates are the main form of alkalinity, this will produce useful results. If 
other forms of alkalinity are also present (such as phosphates), the results 
will be garbage.

>Date: Sun, 17 Sep 2000 11:44:03 -0700
>From: "Dixon, Steven T. (BEn)" <stdixon at ben_bechtel.com>
>Subject: CO2
>Julius Odian wrote:  "[lowering pH with CO2 is bad]"
>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. 

The theoretical equilibrium value is roughly 0.5 mg/l, +/- some based on 
temperature and altitude. Typical values seen in a non-CO2-injected aquariums is 
2-3 mg/l due to CO2 generated by the bioload present. 

George Booth
Keeping those myths from getting out of control