7 Kegs at 25psi and I'm out of Co2, normal for 5lb tank or do I have a leak?

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Jan 18, 2014
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Pretty much the title. I carbonate only water and kombucha, 5 gallons at a time with very little if any head space. Takes about 7 days at 25psi to fully carbonate. I was expecting to get 15-22 corny kegs out of a 5lb tank as per the micromatic website. Noticed lack of pressure today after hooking up a full 5 gallons of water and gauge reads 11lbs wide open.

Is the 15-22 corny keg usage based on a lower psi for beer (like 10-11psi)? This would be an easy answer....Otherwise I am going to spend the evening out in the garage with big ass spray bottle of StarSan......Appreciate any response. I looked online for a calculator that would show yield of a 5lb CO2 based on PSI but I couldn't find anything.......
I would say that is correct, you are doubling the pressure and depending on the temperature you are carbing at you are using a lot more CO2. Look for a chart... temp pressure volumes
carb chart.png
I should have included carb temp in my original post, it's 42f. So based on your chart I am carbonating to 3.59 volumes. How can I use this info for yield?

Also, I checked my calendar and it's 6 (not 7)corny keg's to empty a 5lb tank.
For carbonating your formula is Volumes of Carbonation x 14.7 x .5 x Volume of liquid
Weight of CO2 Used for Dispensing = (Serving PSI + 14.7) x .5 x Keg Volume in Gallons

You have to figure both numbers to get your answer but what you got is pretty close in my opinion.
Additional things that will cause your results to be different than your math would suggest are differences in air pressure (14.7 for sea level) purging keg, leaks, micro leaks and temperature variances.
I feel that you most likely have a leak, as I have been able to dispense and serve a bunch of beer with a five pound bottle. Often times they can be tough to find, small leaks.
I was curious as to my CO2 consumption rate after my 39th keg was finished. So I weighed my 5 lb CO2 bottle to see what was left (4 lbs). Since I had already used 3 bottles CO2 to date, my consumption was 16 lbs total. 39 kegs/16 lbs CO2 = 2.44 kegs/ lb CO2 (or 12.2 kegs per 5 lb CO2).

I force carbonate and serve at 12 psi at 42F for all my brews. It's the same setting always since I have a regulator with two seperate low pressure outputs and it's not convenient to change the setting for different kegs.

As a reference, per Northern Brewer, a 5 lb. tank should be able to force-carbonate and serve eight to ten 5-gallon kegs of homebrew.

So I'm all good with my set-up and consumption rate.
You have a leak. I use around 100 grams of CO2 to carbonate and serve a single keg.