I tried a search or three and came up empty on this one...so hopefully I'm not repeating some oft-asked question. After my first 7 brews were quite successful, I'm finally going to start kegging some. Due to space limitations, I'm stuck with the bottom shelf of our garage fridge. A keezer may happen eventually, but is several years away. Back to my question, because of these limitations (17" height), I'm limited to a 2.5-gallon keg and a 2.5-lb cylinder. If I plan to force carbonate, how many kegs per tank should I expect?