re: pH of RO water.

[jlemons at myriad_net]

>Dr. Joseph R. Sachleben
>Research Scientist Campus Chemical Instrument Center
>The pH of RO water will start out near what the
>tap water was. The pH of DI water will start out
>neutral. After sitting out a while, both will
>go to a pH of about 5.5 because of CO2 disolving
>into the water.

Assumption 1:  This guy knows his stuff
Assumption 2:  I sure as heck don't
Assumption 3:  I'm confused...

Question 1: My tap water is pretty much crap for growing plants.
Its got a pH of about 8.6-8.8 depending on when I measure it.
Its also hard as nails.  The RO water I get from it has a
measured pH of 7.0-7.2.  Is this measurement wrong?

Question 2: After being in the fish tank for a while with injected
CO2, the pH dips to about 6.6-7.0 depending on when I measure
it.  Is this correct, or do I have a screwy test kit?

pH of RO water.

>
> Hi all,
>
> The pH of RO water will start out near what the
> tap water was. The pH of DI water will start out
> neutral. After sitting out a while, both will
> go to a pH of about 5.5 because of CO2 disolving
> into the water. The H2CO3, HCO3- buffer system
> ends up being the buffering that naturally occurs
> in RO/DI water.
>
> Joe Sachleben
> jsachleb at chemistry_ohio-state.edu
>
> ***********************************************
> Dr. Joseph R. Sachleben
> Research Scientist
> Solid-State NMR Facility
> Campus Chemical Instrument Center
> The Ohio State University
> Johnston Laboratory 119
> 176 W. 18th Ave.
> Columbus, OH 43210

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