You can actually build your own CO2 generators VERY inexpensively. The
following is a rather exhaustive discussion:
http://www.qsl.net/w2wdx/aquaria/diyco2.html

For what it's worth, I do the following:
get a jug with a flat bottom and a rubber liner in the cap
get some tubing; six feet is usually more than enough for me
get a check-valve
drill a hole in the cap of the jug that's slightly smaller than the
tubing
cut the tubing diagonally so you can fit it through the hole; pull hard
to get the whole thing in
cut the tubing somewhere and install the check-valve
mix 1/2 tsp yeast, 2 cups sugar and 1.5L water in the jug
(I use 4L jugs, so my mixture is 1/2 tsp yeast, 4 cups sugar and 3-3.5L
water)
recharge the jug about every two weeks

I have about five or six of these things running. On my 37g tank, I have
two, which I replace on a staggered schedule (one's always going while the
other's off the system).

I put small plastic "cups" on the bottoms of my filter intakes, which
capture the bubbles and release them into the filter, where the impeller
disperses the gas. I've also drilled holes into the intake tubes, but I
find this causes me annoyance when I do anything involving the filter.

This system is really simple to produce, is dirt cheap, and makes me feel
like a DIY hero. I haven't won a Nobel Prize as a result, nor are
attractive women begging me for dates because I'm the CO2 King of
Mississauga. Your results may be better than mine, so at least give it a
shot.

I've read that if you use a good yeast, you can actually drink the alcohol
produced. I've read too many wives' tales about people going blind on
moonshine, so you won't see *me* trying it anytime soon!

Have fun, William;
Duncan

"william kossack" wrote in message
...
I have not gone to CO2 yet because of the price.