Re: CO2 thoughts...

> From: psears at emr_ca (Paul Sears)
[snipped Olga, George & Paul's comments on CO2 pH buffering]
> 	Where the higher KH _does_ provide useful buffering is when
> other acids are being added (e.g. nitric as the ammonia produced by
> the fish is oxidised).  The pH will stay in a (relatively) narrow range
> until just about all the bicarbonate is gone, and the more you have,
> the more acid addition you can take before the pH crashes.  At that
> point the KH is just about zero.

Does this oxidation of ammonia to nitric occur when ammonia/ammonium 
is being metabolized by the plants or during biological consumption
by bacteria? Does this amount to a net consumption of carbonates? What 
happens to the sodium or calcium ions? Does it mean that carbonates need
to be replenished regularly through water changes and possibly additions
of chemicals? In the absence of sufficient CO2, a planted aquarium will
increase in pH due to biogenic decalcification (calcium precipitation).
Would there be a net pH increase without intervention? (assuming plants,
fish, CO2, lights, food and no other chemical inputs other than distilled
water to make up for evaporation)