DIY CO2 Generator

I have noticed a lot of notes about DIY CO2.  Here is what works for me.

I use 2 liter Gatorade bottles because the plastic of the bottle and
especially the cap (more on this later) are thicker.  I use a .5 liter
mineral water bottle for a bubble counter.  This extra piece of hardware
keeps the "mysterious white gel" from forming on your airstone or
elsewhere in the tank.  I have used both nylon and silicone airline
tubing, and find both work well, but the silicone seems to leak less.

I drill 1 hole in the Gatorade cap, and 2 in the water bottle cap, about
half-way between the center and the edge.  I make this hole _slightly_
larger than the _inside diameter_ of the airline I am using.  This
allows the tubing to form a tight seal with the cap, preventing the need
for any form of sealant.  A length of airline is inserted in the
Gatorade cap 1/4", and through the water bottle cap to reach 2/3 into
the water bottle.  A second airline goes 1/4" in the water bottle cap
and into the tank.  I use an airstone in the tank, but you can use
whatever "reactor" method you prefer.

The airline fits snugly, does not leak, but can be removed easily.  I
feel an added measure of safety in that the airline will slip-out of the
bottles if the CO2 pressure ever gets too great. (A built-in pressure
relief!)  The thicker plastic forms a better seal, and is less likely to
explode.  ( Also, these types of bottles have expansion-relief designed
in with ridges of plastic which will "pop-out" if pressure builds up.)

Before adding water to the small bottle, or water-sugar-yeast to the
larger one, I connect everything but the airstone, and connect the "tank
line" to an old air pump.  This pressurizes the entire contraption to
check for leaks ( so far with this set-up, I have never had a leak.)

Finally, I add 1c. hot water and 3/4c. refined sugar to the large
bottle, mix well, add 4-5c. water, and 1tsp. bakers yeast, and shake
well.  I let this set for 30 min. before filling the smaller bottle 1/2
full of water and adding the airstone to my tank.

Trent Honea