I am currently learning about bacterial roles and how they function in different environments and what not, so im reading about aerobic and anaerobic bacteria, and the forms of cellular respiration used in each. Then I come across an assignment where we have to pick a unicellular fungi/bacteria, I chose yeast. Yeast in an anaerobic environment relies on fermentation to create energy, the by product is C02. My epiphany = using yeast for C02 supplement in a planted tank. I did a quick google search, and found an article explaining the science of it and a DIY yeast reactor kit. I soon found myself intrigued by the article, finishing it at 2:17 this morning. Give it a read, maybe it will inspire you the way it did me. All this semester I was pretty rattled about how useless the topics taught in biology were, until today.
http://www.qsl.net/w2wdx/aquaria/diyco2.html