CO2 Generator Kit (5L)
This Mother Nature CO2 Generator is supplied with an air pump which can be used to circulate CO2 into the air around your plants to enhance their overall development.
The amount of carbon dioxide in the air is the main limiting factor when growing hydroponically, as water and nutrients are generally sufficiently provided. The ambient levels of CO2 are enough, but as that gets used the amount of available CO2 in a closed environment obviously becomes depleted. If the CO2 is not replaced, plant growth halts. So really, you want to be ensuring that a good amount is always available.