CO2 tank advice

[gone fishin]

Could anyone give me a guestimate of how long a 5lb CO2 tank would last in a heavily planted 55? I can get one locally at a good price, but Im also looking at a very nice 125 and i dont want to sell myself short. The next size up is a 20lb and that creates a space issue. Any help would be appreciated.

 

[AlexPerez]

My 10 lbs last about 6 months, so for a 5 lbs I would guess about 3 months.
It would also depend on how much CO2 you put in, how much CO2 gets outgassed, how much CO2 your plants use relative to the lights you have.
If you run CO2 24/7 or not.

 

[malkore]

My 5lb tank lasts 10 months on my 75gallon setup, running 24/7.

Also, there is a 10lb tank, thats about the same height as a 5lb, but is a bigger diameter. From what I've heard, a 10lb tank is only a couple bucks more to fill than a 5lb.

But as Alex points out, every tank is unique, and will need a different amount of injected CO2. Plus not running 24/7 (via timer or pH controller) will cut CO2 use quite a bit.

 

[BASSNMAN]

As other members have stated, 3 to 6 months but will depend on rate of application. When I was shopping for a bottle, I called several different welding supplys. The prices do vary considerably. A 10 pound was only $18 more than a 5 to buy and only costs $6 more to fill.