We sell 20 and 50 pound aluminum CO2 tanks. They are about 1/2 the weight of standard steel tanks. Use the best CO2 tanks available. Complete with plastic collar to prevent damage during transportation and use. Certified for CO2 use only. They do not come filled. If you're confused or have questions about CO2, check out our CO2 buyers guide. Want to know know long your tank will last in your growing space? Using a co2 calculator will help you use your CO2 efficiently.