DR. MOSS CO2 Diffuser 9Spiro glass CO2 Diffuser - Aquarium Moss Fern Plant ph The high efficiency of diffusing carbon dioxide. CO2 bubble counter is built in this device. Easy to install and use, with no extra power required. Suitable for tanks 40 - 75 gal (120L - 280L). For 4/6mm co2 tube (exclude),only use with co2 cylinder.