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RE: Planted Goldfish Tank (was: a few questions)

>Well, this raises another question then: Is the artificially lowered pH of
>CO2 injected tank really the same thing (chemically and/or biologically) as
>the pH of water that has a lower pH due to other reasons? I can't see how
>the pH of water that is lowered by oak leaves or barley is the same as
>affected by CO2 injection, but I'll admit to being nonconversant in this
>any) kind of chemistry. Perhaps a chemist on the list can step in. How does
>CO2 affect a calculation that involves H?


Since biology is just chemistry on a smaller scale (I can feel those burning
flames...) then yes, the pH set by "chemical" means is the same as from
"biological" matter. Also, the lowering of the pH from CO2 has the same
origin as that from tannins, muriatic acid, and other water acidifiers like
sodium monophosphate and sodium monosulfate. Without going into a lot of
math and chemistry, water falls apart on its own to a very small degree:

2 H2O -> H3O+ + OH-

H3O+ lowers pH and OH- increases pH. In superclean water their amounts are
the same and the pH is 7 (neutral). Muriatic acid lowers pH by producing

HCl + H2O -> H3O+ + Cl-

The other two acidifiers that you can buy in your LFS, sodium monophosphate
and sodium monosulfate also produce H3O+

NaH2PO4 + H2O -> Na+ + H3O+ + HPO4--
NaHSO4 + H2O -> Na+ + H3O+ + SO4--

Tannins are also acids and you can write them as HA, where A stands for an
acid with a complicated structure:

HA + H2O -> A- + H3O+

The bottom line is, whatever acid you use, it will produce the same H3O+
that you measure when you check your pH. Different acids produce different
amounts of pH, though, and that is why you get a lot stronger effect with
muriatic acid than with tannins.

Slawomir Janicki
janicki1 at earthlink_net