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.