C02 Systems? How? What?

CO2 is a carbon dioxide that is required by plants just like oxygen is required by animals. Carbon dioxide produced by fishes might not be enough for plants to grow well, that is when co2 diffusers r used. Java fern and moss will do alright in low light water without co2, they r very hardy plants, i have them in my 40 gallon goldfish aquarium. They can do well in cold water, warm water,brakish water, low light, high light whatever.Java fern grows best while tied on a driftwood or rock. To learn how co2 diffusers work, check videos on youtube, they have many videos where u can make ur own co2 reactor at home.