Buffering KH & lowering pH, with no CO2 (yet)

> From: Mark Wickersham <mwickers at minerva_cis.yale.edu>

> I discovered [a pH drop] was most likely due to a deficiency of CO2
> for the plants, and that they had begun to remove the calcium
> carbonate from the water to do their photosynthesis routine.

No, this is "biogenic decalcification" and it will cause the pH to
rise.  Since your water was pretty much unbuffered, any increase
in acids (for instance, from dissolved CO2 in the tapwater) would 
cause a rapid decrease in pH.

> I think David and others have said they have used vinegar to achieve
> the drop.  That's the only method I've heard thus far, other than
> installing a CO2 generator.  Are there any other ways to do this?

All the techniques except CO2 will turn your water into chemical
"soup" and you will loose all control over what happens.  If you don't
want to invest in CO2, reduce the KH to 2 degrees and live with the 
higher pH (7.4 to 7.6).  A stable pH is better than one which
constantly changes due to external fiddling.