C02 Bottle size

How big of a co2 bottle do you guys use?? I am going to be running 4 kegs and was told by the homebrew shop that a 20lb would be the right size but from what I am reading most of you are running a 5lb or a 10lb.
How long does your bottle usually last??
I am new to this guys so I apologize if this qestion seems silly.

I use a 5# to push and force carb 3 kegs at a time. The kegs go pretty quick, but the tank still lasts at least 4-6 months. There's no harm in going larger if the tank fits your budget and your setup, but 5# is certainly viable for most folks.

At my supply store where I bought my tank it was the same price for both a 5lb and 10lb tank. There is a difference in price of about $1.50 when refilling it, so out of economics I pretty much had to get the 10lb tank. I have a Sanyo 4910 and the 10lb tank does fit fine. I just have to tilt the regulator a bit, but all is well.

I have two 5lb tanks. One's on my 4 tap kegger, the other is for other. I have a keg of soda water that gets replaced three times a month and I still get 3-4 months from a tank. I'd rather not haul around anything bigger.

i have six tanks. a 50#, 3x20#, 10# and a 2.5# for absolute emergencies.

the 50# i expect to last for over 5 years (sorta a problem since the hydrotest is only good for 5 years...), as long as i have no leaks, since i only use it for serving (it is almost 200 lbs, so i'm not about to move it). my 20# tanks seem to go pretty fast on me now, but that is because i am very wasteful with co2, and use it for closed transfers from my fermenters to other fermenters or to kegs, as well as purging out anything i don't want oxygen in.

if you are conservative with your co2, a smaller tank will work fine for you given you don't go through that many kegs. with that said, i would recommend the largest tank you can afford and move around if it is going to be your only tank.

i guess i should say i also have a 6 faucet kegerator and 35 kegs (only about 15 are filled with beverages right now though, and i generally use 6 or so to hold RO water for brewing).

i find the 20# tank to be the best compromise. it is more economical to fill than the smaller sizes, yet is easier to move than the 50#. for most people, a 20# tank should last well over a year with a reasonable amount of use.

I much prefer having 3 smaller tanks than one larger one. I had a 20# tank but I traded it for 3 5# ones and I find that much easier for a variety of reasons:

-I always have CO2. When I run out on one tank I can swap it out and all is well.

-Portability. A 5# tank is very portable so I can take a keg of beer to a picnic, party or other event.

-Fits inside the smalle kegerator. No way my 20# would fit inside the kegerator I have and it looks a lot cleaner and more professional to have the tank inside the fridge when it's sitting in your dining room (like mine does).

-Ease of handling. a 5# tank weighs less than a keg of beer. I can carry it (especially the aluminum one) with one hand.

-No one has every taken me up on this but.... if a buddy ever ran out of co2 on a weekend I'd be able to hook him up just by handing him one of my spares.

Thanks guys for all your feedback. I think I will end up going with a 20 for my kegerator I am building and have a 5 on hand just in case.
Thanks again guys.
I wish I would have gotten into this obsession years ago!

Keep in mind its cheaper per pound to fill a larger tank. Getting a 5# tank filled may be 10 bucks, where as a 10# tank possibly would be $12.

Anyways... we're only talkin a few bucks here... I would first buy a tank thats the physical size you need and that matches your portability requirements.

that sounds like a good compromise. having multiple tanks on hand is always a good thing, as you tend to run out of co2 just as you need it the most.

keep scouring craigslist though. that's where i bought all my tanks from, and they were CHEAP. usually around 20 a piece. always out of test, so it ended up costing me around 50 per tank (the hydro test costs around 18 dollars, and the fill around 12, plus the cost of the tank). but that is still cheaper than buying new or from the welding supply shop. i think i was quoted 160 to purchase a 20# tank from the welding suppply shop.

A question popped into my head while reading this thread; for those of you with 20# tanks, exactly how big is it? What are the dimensions?

I can lease a tank from the local welding supply shop (just have to put down a deposit) and fill it for about $20....but I haven't really thought about the size and whether or not it will fit in my fridge....

28" tall here and about 12" wide when considering the regulator width also. Keep in mind thought that some of the tanks differ slightly.

Thanks, you gave me another reason to go down and get another beer!

My 20lb is about the size of a corny keg. I want to get one that will fit over the hump in the chest freezer which I think is 10lb, but I won't buy new.

craigslist, or go to the local welding supply shop to see what their prices are like. you may even have luck on ebay.

I've run well over 100 gallons through my tap with a single 20# tank, and it's still "in the green."

you probably already know this, but the high pressure gauge isn't linear with the capacity of the tank. since co2 is stored in liquid state in our co2 tanks, as long as there is liquid left, the pressure will remain unchanged at a given temperature. once it starts dipping though, you have to be very careful, as you are literally running on fumes at that point since there isn't any more liquid to vaporize.