Hagen's CO2 Natural Plant System helps release the natural beauty of your planted aquarium! CO2 diffusion, through natural fermentation, results in a dramatic difference in plant growth, condition and color. As a result, water quality is enhanced, benefiting fish condition and health. Plant System includes Fermentation Canister, CO2 Bubble Counter/Diffuser, 3 Activator and 3 Stabilizer packets (up to 3 months supply), CO2 Resistant Tubing and Suction Cups. For aquariums up to 20 U.S. Gallons. Larger aquariums may require more than one unit. Shipping weight: 1 3/4 lbs.