CO2 question
 

Will activated carbon filter out CO2?

No.

No but it will filter out the nutrients in the water.

Activated carbon won't absorb the aquarium carbon dioxide but it is best not used unless you are prepared to use nutrients daily. Your aquarium plants will still grow fine with carbon in the filter but if you are concentrating on the plants rather than the fish then don't use it.

:shock: In a tank lacking CO2 injection, Activated carbon can hamper plant growth by limiting what little is produced without CO2injection.