Aquarium CO₂

If you have a freshwater-planted aquarium, you have probably heard of CO₂. It is the magic ingredient that all of the best tanks use. But why do you need to add CO₂ to your aquarium? And how do you add CO₂? Find out the basic concepts, and then in the Advanced CO₂ Section delineate the individual components of advanced CO₂ systems and describe how the components work together.