Ista CO2 Carbon Dioxide Diffuser Supply SetThe convenience of not having the hassle in refilling cylinders Ideal for Nano Tanks. These sets can be easily adapted to any kind of tank, even plug and play tanks. Ideal for beginners, and low light tanks, with low demands for CO2. The CO2 could last for months, if setup correctly. For low light tanks, the rate of 1 bubble every 5 seconds can guarantee the usage for months. Place the CO2 diffuser to the very bottom of the tank to achieve the best