Snagged a great deal on a 20lb co2 tank back in April ($10!! yes really!!); it went online on May 1st. Still going strong, and I brew at least 3 batches a month, all kegged, and force carbed. Curious to see how long a 20lb lasts for others. My little 5lb tank would last about 3 months; doing the math, that means I should get close to a year from the 20. Thoughts?