How do I know?
It's not my knee.
My C02 levels have never been as constant as I would like (BBA). From time to time I notice my reactor would cavitate(sp) / burb and, in the worst case, my fish would be up near the surface gasping by the time I got home from work.
I started noticing that...
Here's a collection of DIY CO2 articles that include directions
for making various reactors, yeast recipes, and CO2 bottles units.
DIY CO2 References - Understanding the Basics of DIY CO2 diffusion with how to guides
Comprehensive DIY CO2 Report - reasons for CO2, DIY bottles, yeast...