Making a CO2-system 16.10 2006
Today I made a CO2-system that works through fermentation for a 28
First picture displays all the necessary equipment for making a CO2
system: hammer, nail, 2 bottle caps, a 0.5 liter sodabottle, the neck
of a 0.5 liter juice bottle, a suction cup, a piece of silicone tubing
Second picture: I made a starting hole on the bottle cap for the
scissors using the nail and a hammer.
Third picture: I enlarged the hole with scissors. The hole should be
small enough that the silicone tube will just fit through it.
Fourth picture: The silicone tubing fits the hole exactly, now all that
is needed is to make it airtight with silicone.
Fifth picture displays the ingredients needed for the fermentation
process: the sodabottle with appr. 3-4 dl water, sugar, a measuring cup
(1 dl) and fresh yeast.
Sixth picture: I measured roughly half a deciliter of sugar in the
measuring cup and a small cornerpiece of the yeast.
Seventh picture: Now the fermentation bottle is ready, all you have to
do is attaching it to the CO2-spreader in the tank.
Eighth picture: Next I made a passive CO2-spreader. For that I needed a
bottle cap, a suction cup and the neck part of a juice bottle.
Ninth picture: I made a hole in the cap as well as the side of the
bottleneck using a nail, a hammer and scissors.
Tenth picture: I attached a suction cup in the hole made on the side of
the bottleneck so that it could be attached to the aquarium glass.
Eleventh picture: I attached the tube from the fermentation bottle to
the cap screwed on the spreader.
Twelfth picture: It's ready. The spreader has been attached to the
aquarium glass and the fermentation bottle is hidden behind the
Reloading the fermentation bottle and some hints:
A 0.5 liter bottle of this mixture will produce CO2 for approx. 2
weeks. When no CO2 is produced it's time to make a new mixture. Empty
the fermentation bottle of water so that you're left with the yeast
sediments. Then add roughly 0.5 dl sugar and 3 dl water. If the mixture
doesn't start fermenting, add a small piece of yeast.
If fresh yeast isn't available, you can also use a small amount of dry
yeast, the tip of a teaspoon should be sufficient. Keep in mind that
dry yeast requires higher starting temperatures than fresh yeast.
The bottle generally doesn't start producing CO2 immediately but
usually the next day. If this doesn't happen you either have a leak or
it's too cold for the fermentation process.
If you want to make sure the fermentation mixture won't get to your
tank through the tube, it's worth investing in a no-return valve and
attach it somewhere along the tube. These are sold in hardware stores
and well-equipped petshops.
If the room temperature is too cold for the fermentation process, ie.
it's not producing any CO2, you can give the bottle some extra warmth
by placing it on top of the aquarium light, wrapping it up in a woollen
sock or some other means.
Author: Aleksi Kinnunen
Translation: Minna Lintu