| | Re: 5lb CO2 tank empty in 2 months
depends on the aquarium size and amount of CO2 you dispense and whether or not you have the CO2 regulator on a timer.
For me, I use less than a bubble per second on a 14 gallon tank. My CO2 shuts off when the lights do, (on for about 9 hours a day) and I haven't filled it up in over a year. Granted, it is time to refill it now after 19 months.