Re: Aquatic Plants Digest V2 #91

> One for the chemists...
> Karen writes:
> > 
> > As far as I'm concerned, I have yet to see a method of reducing pH 
> > in a planted tank other that within the carbonate buffering system 
> > (i.e. using CO2) that is better for the plants  _or_ the animals 
> > than just leaving the pH alone.  People who mess with the pH in 
> > other ways are doing it for themselves, not for the tank 
> > inhabitants.  

	It really comes down to the buffering ions... You can add large
organic acids, humic acid, tannic acid, etc., which are in peat extract.
If you water is really soft, these compounds can easily lower pH into the
5's, depending on how much you use. While the pH may not be optimal for
plant growth, and the water coloration does not help the light
penetration, the chemicals have algal, bacterial, and fungal inhibitors.
However, Karen is right, any acid (other than ones with CO3-2) will
deplete the KH in your tank and you will be fighting to balance it out --
although, the organic acids do not deplete the KH as fast as small acids.
The thing is that it comes down to is the buffering system. The reason why
you cannot use anything other than CO2 is because you are working with
CO3-2.  If you wanted, for some unknown reason, to buffer using PO4-3,
NO3-2, or something else, you could do all sorts of other stuff.