For Nyberg’s recipe for Do-It-Yourself CO2:

http://www.aquatic-gardeners.org/Nyberg_yeast.ppt#256,1,

For brief summaries of how to make a co2 yeast reactor from Karen Randall:

http://www.aquarticles.com/articles/plants/Randall_carbon%20dioxide.html

http://www.fishchannel.com/media/freshwater-aquariums/planted-tank/revisiting-reactors.aspx.pdf

PICTURES

1. The CO2 bottle itself. Notice the silcone adhesive seal on the rigid tubing and the black, CO2 tubing heading towards the check valve.

CO2 bottle for yeast reactor

2. The t-valve. This is optional, but I like the consistent production of CO2 you get by connecting two bottles for use on one tank.

T-valve

3. The check valve.  Since a check valve only allows gas (or liquid) to flow one way, make sure it flows towards your aquarium!

check valve

4. Insert airline tubing into power filter intake. You can use scissors or needlenose pliers to make a small hole in the intake strainer. For the shot, I removed the intake tube from the filter, as it would have otherwise been hiding behind my plants. 🙂