Materials you will need:
Two liter soda bottle (or, better, an airtight rigid plastic bottle)
This carbon dioxide reactor will help your plants utilize the light
that they are getting to maximize photosynthesis. It functions on
the simple principle that the bi-product of yeast metabolism includes
carbon dioxide (CO2). The idea is rather simple. Simply
take an empty two-liter bottle and drill a small hole in the cap.
The hole should be large enough to push the nozzle of an airline
fitting through.
You want the hole large enough for the nozzle to fit through easily
without the air tube attached, but with the air tube covering it the
fit should be very tight. In this way the air tube will form an
airtight seal.
Once you have the hole drilled, run the length of tubing into the
hole starting from the top outside of the cap into the cap. On the
end of the line that is on the inside of the cap, attach one of the
airline fittings. It doesn't matter if it is a T type or an elbow,
as long as it is small enough to fit inside the cap. Next, pull the
airline back snugly so that the fitting is pulled into the hole in
the cap, with the airline forming a seal between the nozzle of the
fitting and the inside of the hole in the cap.
Congratulations, that is the hardest part of this contraption. Next,
fill the bottle
with one cup of sugar, one tablespoon of active yeast and about one
liter (half the bottle) of water. Shake well by placing another
intact cap on the bottle. Remove the intact cap and screw your new
"cap with airline tube" onto the bottle containing the
yeast/sugar/water mixture. Place in an upright position near the
aquarium.
CAUTION! Be sure that the bottle will not tip over or the mixture
will flow into the aquarium and cause disastrous results.
The CO2 creates pressure and will pump the liquid into
the tank if the bottle is overturned. Also be sure that the bottle
is placed at the same height as the aquarium. If it is too low, the
water from the aquarium may siphon down the tube and overfill the
bottle, possibly leaking out onto the floor. If it is too high, the
opposite may occur- the sugar/yeast mixture may siphon into the
aquarium.
Next, place the end of the airline into the aquarium where the
CO2 can bubble into the water. A good place to put it is
in the intake of a power filter tube, where the bubbles will be
dissipated before the water is returned to the aquarium. Be warned,
though, that if the intake flow is great it may collapse the bottle
and pump the contents into the tank. For this reason it may be
preferable to use a durable container of rigid plastic or even glass.
The reactor should begin producing bubbles in a few hours, and it
should continue for a few weeks. Results vary greatly, and you may
find different recipes on the web with claims of possible
improvements in them. When the reactor stops bubbling, simply mix
up a new batch of sugar/yeast mixture.
Airline tubing, preferably silicone
Airline fittings, preferably plastic
Drill
Sugar
Yeast