DIY CO2 in the cold and other animals...

["Wayne Jones" <waj at mnsi_net>]

There are many ways to improve a yeast CO2 generator:

#1 Make sure you do not have any leaks. You can test this by pinching
off the CO2 line and putting the fermentor underwater.

#2 The best way to attach the CO2 line to the fermentor is with a rubber
stopper. The second best way to attach the line is to drill an
ubdersized hole in the bottle cap, cut the CO2 line at an angle and pull
the line through the hole with a pair of pliers.

#3 Bread yeast doesn't work very well. Use champagne yeast or in your
case use something that will work well in cool temperatures such as ale
yeast.

#4 Use two fermentors with offset starts to keep CO2 production more
constant.

#5 Don't add more sugar than necessary. This depends on your yeast. Some
are much more tolerant than others of high alchohol. For wine yeast use
about 1 cup per 32 oz quart. Use much less for beer or bread yeast.

#6 Use baking soda to buffer the fermentation so that the pH does not
drop too low and kill the yeast.

#7 If you need more CO2 use a larger fermentor and increase the recipe
proportionately.

#8 Don't use a lot of yeast to start with. If you use too much,
production will start too fast and drop off quickly. If you use too
little basically nothing will happen. If you use champagne yeast you can
add more yeast later as the production starts to fall.

#9 Fermentation rates are strongly influenced by temperature. When the
temperature range is too low production falls and when it is too high it
falls again. You can keep your bottles warm by putting them in a bucket
of water with an aquarium heater or you can put them close to your
ballasts if you have remote mounted ballasts. The latter method sort of
coincides with the light period and is way more convenient. It's too bad
it takes so long for the bottles to cool down.

#10 Float your yeast before adding it to your fermentor especially if
you are adding yeast to an already started fermentation.

#11 Use rigid fermentation bottles. That way you can just inject CO2
into the intake side of whatever pump you are using without collapsing
the bottles. This is a pretty darn good difuser just by itself. Just
make certain that in the event of a power failure that the CO2 gas won't
be trapped in the impellor area. If this happens the pump may not prime
and ruin your impellor. I drill a tiny hole just past the pump output so
the gas can always escape. Wet/dry filters can also be used as CO2
difusers.

#12 Use a backcheck valve. This is necessary to prevent siphoning if you
do inject CO2 into the pump intake.

#13 Use a copper penny in your fermentor to suppress the production of
H2S. No idea if it works but it doesn't cost much.

#14 Make a bubble counter out of a 500 ml pop bottle and a rubber
stopper. This can double as a washer bottle to help contain methanol.
Change the water when you empty the fermentor. Bubble counters on this
kind of system usually don't work properly without a check valve. The
check valve adds just enough back pressure to prevent multiple bubbles
from coming out.

#15 Some people have success with a continuous fermentation but I could
never get it to work well. The idea is to make a fairly weak solution of
water, yeast nutrient, baking soda and sugar. Add the sugar mixture to
your fermentor and inoculate it with ale yeast. When CO2 production
starts to fall, decant some of the liquid in the fermentor and add more
of the sugar mixture. You should be able to keep this going for a long
time. You waste some sugar but you save on yeast. I would like to learn
more about this one.

#16 Very nearly 50% of the weight of sugar is converted to CO2 gas if
your fermentation is a good one. Most people create an incomplete
fermentation by not providng any nutrients for the yeast so they end up
throwing away most of their sugar. The best way to check this is with a
hydrometer. A good final fermentation often has a negative S.G. if you
didn't start with too much sugar.

#17 No matter what you do yeast CO2 will never be as good as compressed
CO2 but contrary to popular opinion it can be competitive in price. The
method in #15 should be very inexpensive for small tanks if you can get
a steady CO2 production.

#18 For small tanks you can use a CO2 bell as a difuser. The area of the
bell regulates the CO2 concentration. The more water movement in the
area of the bell the more efficient the difusion. They get pretty
cumbersome on large tanks.

#19 Larger fermentors last a little longer and have more even
fermentation. It is better to have 2 large fermentors than 4 smaller
ones. Less work and same CO2 production.

Wish I could think of another one to make it an even 20 but that's all I
know about it. :-( The ideas at the top of the list are generally more
important than the ones at the bottom of the list.

Wayne