5 lb refills cost me $20. 20 lbs cost about $25, maybe $30.
Definitely some economies of scale.
I run a 50 pound tank for my primary kegerator, and a 20 on my lagering/carbonating fridge. Go big or go home. It costs $12 to fill the 20#, but the 50# only costs $20 and has so far lasted 3 years, maybe 4 and pushed about 600-800 gallons of beer. Yes I drink too much beer.
I get fills for $2/lb at the LHBS. That is slightly cheaper than the fire safety place. Last time i got the 20 filled it was about $18 at the fire safety place. Paper work and time is the cost, the CO2 not so much. The 5 goes to the LHBS. The 10 goes to the LHBS if the fire safety store is not open - more limited hours. You can figure where the 20 goes.
Would a 5 pound CO2 tank run 4 5 gallon kegs? I am working on a 4 draft kegerator system and plan on getting a bigger CO2 tank at some point down the road. Wondering if a 5 pound CO2 tank would get me by for now.
If you’re only using it to carb and serve (no purging, etc.) you should get about four kegs per pound of CO2.
I have a 50, 20, and 4 5’s. I would say 20 is probably the best of both worlds as far as being able to move it around and still get a decent price on a refill. The 50… ugh… It’s pretty cheap to get filled but man can it be a chore to get back into my second floor condo when filled :D The tare weight on the tanks can run between 100-150lbs. So you’re looking at a rusty tube that weights 150-200lbs when you bring it back from being filled or swapped…
Larger the better. 10# an 20# only cost slightly more than a 5# to fill. A worker told me that the most expensive part is hooking the tank up and the co2 is cheap. Also, you can buy cheap tanks online at Craigslist, but they must have the ID tags. If they don’t, places won’t swap or fill. I use a 10 and fill every 3 months or so and a 5 I fill if, I have “extra” money, to force carb separately.
Any co2 tank should work. They will look at the last hydro test date stamped into the tank though if you want it filled. You need to have it hydro tested within 5 years or you shouldn’t be able to get it filled. They hydro test is usually about $20.
One benefit of swapping, at least in my experience, is longer times between needing to pay for hydro tests. The airgas I swap at is sure to give me a tank with the same or earlier date.
Yeah I tend to swap out my 50lb tank, but once you get a ‘good’ one I usually stop swapping. The 50lb tanks seem to vary considerably. My first tank had a tare weight of 100# and this last one I swapped it for has one of 150#. Made a significant difference when I went to carry it from my car to my 2nd floor condo…
Earlier?
Oops, I mean later. 
Example: I give them a tank due August 2015 and I get a tank due January 2016. I don’t think they dig through all of their tanks, most likely find the best tank on the outside edge of the pallet.
You swap at every fill? I only swap when I need a retest. Otherwise, they fill the tanks I bring in.
They were out of steel 20s last year or so when I went in and I got the bonus of swapping to an aluminum tank. Which is nice with the larger tanks.
Yep. I find it’s faster and basically the same price. I’m normally in and out in 5 minutes. I have 2 10lb tanks, but may upgrade one to a 20lb next time around.
Just an fyi. Check your local suppliers before getting a 10lbs tank. Fills are never an issue, but when mine came up recertification, I could not find anyone actually willing to do the testing local. The best I got was an Airgas guy who definitely did not want my business (“you can bring it in and we’ll ship it off to our testing center 100miles away and you may get it back if you’re lucky”).
Everyone and their brother would do an on-site swap for a 5 or 20lbs tank. The 10lbs just seemed to be an uncommon size around here and no one other than Airgas even said they might recertify it. No one I found did swaps.
I’m hoping the “May or may not get it back” comment meant your tank versus a comparable.
I found a guy here in Des Moines who only does CO2, mostly industrial and bulk beverage type work, who certified, stamped (Tar weight and full) and labeled a 2.5lb tank for me. He thought it was “stupid” (according to his office lady) but when I picked it up and explained what I was using it for for he decided it was a pretty good idea.
The swap only shops can be expected to limit your options but the small, hole in the wall, places can be very helpful.
Paul
That’s what I thought at first, but he didn’t really reassure me anything would come back. Either way, I’ve moved to a smaller 5lbs tank now just so I can do easy swaps and not have to worry about it. I’m happy to pay a few bucks extra for the convenience of being able to do it at my LHBS.