You don't have to spend a fortune to provide your planted tank with a good source of CO2. The Turbo CO2 Bio System from Red Sea generates CO2 by a pH buffered natural fermentation process, supplying your tank (up to 40 gallons) for approximately 1 month. The system consists of a simple reaction canister that sits outside the aquarium and provides the CO2, which travels through tubing to a special pump placed in the bottom area of your tank. The special venturi pump injector diffuses the CO2 as very fine bubbles, insuring efficient dispersion throughout the water. Connect the pump to a day/night timer to prevent dangerously low pH levels during the night. Economical canister refill kit is available.