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Re: Water Quality Question - Please help any chemists on the list !

John <geohammo at iinet_net.au> wrote:
> Could someone please suggest what I should do to my tap
> water to make it more suitable for plants ? I currently
> do not add anything to the tapwater. Would it be correct 
> to say that my water is very soft and not well buffered ?
> pH - 6.4
> Carbonate Hardness - 10ppm or 0.56 degrees
> General Hardness - 30ppm or 1.68 degrees

Yes, your assumption is correct.
> Another question.  I measured the pH in my 10gal tank and 
> it is 7.0 with the carbonate hardness at 10ppm or 0.56 deg
> and the general hardness at 1.68 deg.
> I am injecting CO2 into this tank with the diy method into 
> the intake of a aquaclear mini.  The tank is kept at about
> 26 degrees, has 30watt of light (warm white and grolux) and 
> is planted with Hygro, Ludwiga, Chain Swords, Java Fern and
> ambulia.  How come the pH is so high compared to my tap water
> and why does the CO2 level seem so low (after reading the
> charts).  I would have thought with such a low carbonate 
> hardness that my water would be acid due to the CO2 injection.
> I have checked the gravel in vinager and it does not fizz so
> there is no limestone and any element in it that could 
> contribute to the hardness.

Using the formula: CO2 = 10e(7.00-pH) x KH(degrees) x 3, 
I get 1.8ppm. Something is definitely not right. My non-CO2 tanks 
at home, I measured them at lunch, were 2.9ppm, 3.2ppm, and 
2.1ppm. Ambient CO2 in water is 2-5ppm. There's something 
affecting your pH, or your CO2 isn't being dissolved. I can't think of 
what it can be right now. Let me think...


Jamie    <"\\\><
Greenwood, SC