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High Volume DIY CO2 Fermenters

---------- Forwarded message ----------
From: "Roy Parker" <Roy.Parker at ix_netcom.com>
To: Aquatic-Plants at actwin_com
Date: Fri, 13 Jun 1997 20:46:32 +0000
Subject: High Volume DIY CO2 Fermenters

> Date: 13 Jun 97 08:00:32 EDT
> From: Doug Valverde <75051.160 at CompuServe_COM>
> Subject: Re: Speaking of DIY CO2
> >> What would happen if you used for example, a 4ltr container and
> doubled the recipe? Would it produce double the CO2 for the same amount of time,
> or would the mix produce CO2 at the same rate for a longer time? <<

> Not an expert but I have used one gallon jars with more then double the recipe.
> I have to assume the quantity of CO2 produced was at least close to double, but
> the reaction time at best was the same and usually didn't last as long.  Not a
> real scientific test though.  
> Doug

My first post to the APD, but have been lurking here quite a few 
months, expecially when it was regularly posted to the newsgroups.

I post due to my homebrewing and winemaking experience.  Doubling the 
capacity of the fermenter and ingredients will have little effect on 
how long the solution lasts.  The yeasties propogate to a certain 
level (X millions of cells per cc, don't remember what X is) 
depending on the food supply (sugar) and nutirent level available.  
So once the yeast population  is established, they consume the sugar 
at a constant rate.  So if a 2 liter bottle lasts 10 days, a 4 liter 
bottle lasts 10 days, but at twice the CO2 rate.  Actually the 4 
liter bottle will last a bit longer since the yeasties will take a 
bit longer to get to the final optimum cell concentration, but I 
think you get my drift.

If you want your CO2 to go like gangbusters, add a little yeast 
nutrient or yeast hulls to the mixture.  You can buy these at any 
homebrew supply store.  This supplies essential amino acids to 
promote yeast propogation.  But beware, because the yeasties 
will consume all the sugar in 3 days at most at 80F! You'll also 
probably end up with a yeast cloud in the aquarium as it will foam 
badly and blow out some of the yeast.  It's additional bioload, but 
probably nothing to worry about in most aquariums.  Big worry is the 
sudden dump of CO2 that can drop pH too quickly.

I've seen some posts by folks advocating adding some baking soda to 
the yeast/sugar solution.  I assume that by raising pH, this slows 
down the yeast propogation.  Beers pH usually runs about 5-5.5, and 
wines down to 1.8 or so, so perhaps I'm making the correct inference 

FWIW, I use a couple cups of sugar in about a liter and a half of 
water for my DIY CO2.  I add nothing else, except some dregs of yeast 
from the bottom of the previous container.  You really don't wat to 
add a lot of dregs....just a few drops.  Otherwise you get some yeast 
hulls (dead yeast) that have all those amino acids in their cell 
walls and act as fertilizers so that the next culture gets going 
faster, and therefore uses up the sugar faster.Every few months I 
rinse everything completely, and start with new yeast (just a pinch) 
to make sure I'm not contaminating the culture with a lot of hulls 
(fertilizer).  My last batch of CO2 quit bubbling in 6 days, so looks 
like it's time to do that cleaning routine again.  BTW, have been 
using the same package of Star bread yeast since September.  You only 
need a tiny pinch to get things going.

Hope this is helpful to someone.  I've certainly gotten a lot of help 
from reading the posts to this list for the last few months.

Roy Parker, rparker7 at ix_netcom.com, regardless
of what Netcom puts in the "reply to" field....
Buckskinner, Brewer, and semi-Handyman
Booshway, 1998 Original SW Reg'l. Rendezvous
Houston, TX, home of the annual Humidity Festival
rparker7 at ix_netcom.com