For Byron, Moneymitch & JDM,
I submitted an article to "Aquarium frontiers" magazine and it was publish in 2002. The title is "AIR QUALITY: The effects of carbon dioxide on pH".
At the time, the article was aimed at the marine hobby but I believe it has implications for the fresh water hobby too. I noticed that you gentlemenl have mentioned where and how CO2 is produced but you have overlooked other sources of CO2. The buildup of CO2 from humans and indoor appliances, especially overnight when all windows are closed and the residence does not have a fresh air intake on their heating/airconditioning system and its well sealed. Take a look at the article and data I presented.
Short Take: Indoor Air Quality: The Effects Of Carbon Dioxide On pH — Advanced Aquarist | Aquarist Magazine and Blog
My email address given in the article is no longer valid.