Fwd: Re: Biogas

["Ed Pon" <edpon@hotmail.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
>

Just speculation and curiosity--What if someone were to get a two liter 
bottle of diet coke and poke a pin-hole, or a nail-hole in the bottle 
and allowed it to slowly mix with the water in the aquarium.  Diet Coke 
is available at my Lucky's supermarket for as little as 69 cents for a 
two-liter bottle when using a Lucky Rewards card.  Will this slowly add 
carbon dioxide?  Will it harm the fish?  How about club soda? 

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