**Contributed by petergwee **

Carbon dioxide is a gas that is readily available around us and dissolves easily in water. Since it is easily available and plentiful, why do we have to care about it when it comes to aquatic planting? The problem all starts when diffusion rate of carbon dioxide differs by almost ten thousand times slower in water than air and that aquatic plants are made up of 43% in carbon in which limitation of it will cause plant problems at certain conditions.

Now, since we know how crucial CO2 is to aquatic plants particularly in a closed environment like an aquarium, how are we going to know how much we have in our water and ways of getting it into the aquarium water? Luckily, scientist have come up with the pH/KH/CO2 relationship to measure the amount of CO2 in water and folks have invented loads of equipments over the last few years to dissolve CO2 into the water efficiently.

For the aquarist, supplement of CO2 to an aquarium can be done several ways. If you are on a tight budget or do not wish to indulge into expensive equipments like CO2 tanks/regulators with solenoid attachments, DIY CO2 using the process of fermentation of both yeast and sugar can be done cheap. However, if budget is not a problem, we do recommend the use of CO2 tanks/ with regulators with solenoid attachments for ease of use and consistency. Do note that the carbon dioxide from CO2 tanks are more concentrated and need to be used with caution as they are highly efficient and can kill inhibitants if injection is done improperly.