Re: Biogas

[Lcrabo@aol.com]

Thomas asks about experiences with DYI CO2 production.

I have kept 2liter bottles with yeast-sugar mixtures in them hooked up to my
tanks for a month now.  There was a 0.5 unit drop in pH (with dH ~5)
suggesting that my CO2 concentration was in the mid teens.  My plants have
responded well and the fish don't seem to care.  There is plenty about CO2 and
plants on the Krib website.

Does anyone know what the effect of organic acids (tannins and others) is on
buffering capacity?  I have wondered about this since I like both plants and
Apistos.  Very soft water (which Apistos like) has very little buffering
capacity, which can result in wide pH swings.  Many of you have written that
all of a sudden you noticed that the pH in your soft water tanks was as low as
3 or 4.  Also, the CO2 concentration will rapidly become too high for the fish
at low pHs (below the low 6's) - you can confirm this by looking at the
standard carbonate-pH-CO2 tables.  I am wondering if peat or black water
extract would allow safe CO2 injection at lower pHs than if this was attempted
in soft water (say, pure RO) without the organics.  How does one estimate CO2
concentration if there are  buffers other than carbonate in the water?

Lars