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Carbing in a unitank

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trevelynzx

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Have an SSBT unitank that i haven’t yet used the carb stone on. Wondering what other uni owners are doing for carbing? I have been doing <5psi pressure fermentation before kegging but am wondering if i should bother to use the carb stone before kegging as well.

is there a “smart” way to carb to a precise volume by watching the pressure in the uni?
 

Blazinlow86

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I use a Spike conical and the carb stone is my favorite part. I generally crash cool close to freezing and add gelitine if required then hold there for 48 hours. I then do my trub/yeast dump and hook up the co2 to the stone and set to 12psi showing on the unitank gauge and not the co2 regulator. 24 hours from then I get very clear fully carbed beer. I like to have a large pipeline of beer so I usually have 6-10 kegs ready to go but they are stored at room temperature in my basement Brewhouse. Carbing in the keg at room temp is a pain. With my process as soon as it comes out of the fermenter it's done and can just be stored warm untill ready to drink. Cheers
 

Qhrumphf

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Have an SSBT unitank that i haven’t yet used the carb stone on. Wondering what other uni owners are doing for carbing? I have been doing <5psi pressure fermentation before kegging but am wondering if i should bother to use the carb stone before kegging as well.

is there a “smart” way to carb to a precise volume by watching the pressure in the uni?
The relationship between temperature, pressure, and volumes of CO2 is well established. At your given temp and pressure, at equilibrium, you'll have your target volumes.

It's the equilibrium part that's challenging. And I don't know of a way to verify that precisely (as in other than by sensory after just waiting) without something like a Zahm.

As said above, if you've got a stone and a regulator you can carb it quite quickly.
 

czmkid

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I let my co2 blow off for a few days then close the blowoff ball valve and let the prv do it’s thing. At 65 this gets me to 1.97 vol co2, which is low for my liking (2.43-2.73) and the style s of beer I make. So then I release the tank pressure in order dump yeast and hops, and use the carb stone (and co2 chart) as I cold crash. The key is to rely on the gauge on the unitank not your co2 regulator but you probably already knew that part. It really is wonderful to be able to transfer under pressure to the keg and have beer that is ready for consumption right away.
 

Qhrumphf

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I let my co2 blow off for a few days then close the blowoff ball valve and let the prv do it’s thing. At 65 this gets me to 1.97 vol co2, which is low for my liking (2.43-2.73) and the style s of beer I make. So then I release the tank pressure in order dump yeast and hops, and use the carb stone (and co2 chart) as I cold crash. The key is to rely on the gauge on the unitank not your co2 regulator but you probably already knew that part. It really is wonderful to be able to transfer under pressure to the keg and have beer that is ready for consumption right away.
This. Exactly this.

Plus a cone under pressure makes harvesting and blowing down after a breeze even if you don't dump it beforehand.
 

marjen

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I also close the blow off tube around day 3-4 and let it naturally carb after that. Usually get to 10-15 psi. I will then cold crash and use the carb stone to carb the difference if needed. Has worked out great so far.
 

Rob2010SS

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I also close the blow off tube around day 3-4 and let it naturally carb after that. Usually get to 10-15 psi. I will then cold crash and use the carb stone to carb the difference if needed. Has worked out great so far.
How do you know if the carb stone is needed after the crash? By sampling the beer or is there a visual cue you use?

Thanks.
 

Vale71

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I think the cue is the value shown by the manometer once pressure has stabilized. ;)
 

Vale71

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Yes, but you can derive the carbonation value from a table that you'll find for example here. You just have to wait for everything to stabilize and then obtain your carbonation value based on current beer temperature and manometer reading.
There are instruments for measuring CO2 in real time but they are prohibitively expensive for homebrewers.

Link to the table: https://www.kegerators.com/articles/carbonation-table-pressure-chart/
 

Qhrumphf

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There are instruments for measuring CO2 in real time but they are prohibitively expensive for homebrewers.
Not just that, but the more inexpensive of the options (a Zahm for about $1k) you'll waste most of your batch just getting reading. For less waste you're talking brand new (economy) car expensive, and it's still a lot of waste.

Alternatively can just taste it. Crack the unitank blowoff, and feed gas slow through a carb stone, and taste it till it's where you want it. Not the most accurate numerically but close enough that sitting at temp and pressure will dial it in, and it's very, very fast (even if you do lose a small amount of aroma in the process, although less than anyone who's not doing a closed pressure transfer would).

But if you're judicious with capping/spunding the beer should be mostly carbed already.
 

Blazinlow86

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No need to overthink this one. You just set the CO2 pressure to the psi required to reach your desired carb level according to the temperature your beer is at. Using a carb stone just does it much quicker. cheers
 

sensei247

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I use a Spike conical and the carb stone is my favorite part. I generally crash cool close to freezing and add gelitine if required then hold there for 48 hours. I then do my trub/yeast dump and hook up the co2 to the stone and set to 12psi showing on the unitank gauge and not the co2 regulator. 24 hours from then I get very clear fully carbed beer. I like to have a large pipeline of beer so I usually have 6-10 kegs ready to go but they are stored at room temperature in my basement Brewhouse. Carbing in the keg at room temp is a pain. With my process as soon as it comes out of the fermenter it's done and can just be stored warm untill ready to drink. Cheers
Just curious- how long (months) have you been able to "keep" a carbed beer in your kegs at room temp? If it is longer, a unitank carb stone seems like a no brainer to keep a pipeline of beer ready.
 

catalanotte

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Just curious- how long (months) have you been able to "keep" a carbed beer in your kegs at room temp? If it is longer, a unitank carb stone seems like a no brainer to keep a pipeline of beer ready.
No experience with a unitank but I have both naturally and force carbonated beer in corny kegs at cellar temp 62-64 deg. They have been good up to 2 months later, could be longer, just haven’t had one sit around past 2 months. I do bleed the head space and top off every few weeks to to be sure there are no leaks.
 

Southern_Junior

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So I’m struggling here. I know to trust the Manometer on the tank, but even with my co2 regulator higher than desired(20psi vs. 12psi desired) I’m not seeing the manometer increase much. Should this take a while?

Process:

Add head pressure through blow off to 10psi reading on manometer.
Set co2 reg to 18 psi and attach to ssb carb stone.
Monitor until manometer reads 12psi and then remove co2.

Problem: have not seen any change in manometer reading in 24 hours.
 

Vale71

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So I’m struggling here. I know to trust the Manometer on the tank, but even with my co2 regulator higher than desired(20psi vs. 12psi desired) I’m not seeing the manometer increase much. Should this take a while?

Process:

Add head pressure through blow off to 10psi reading on manometer.
Set co2 reg to 18 psi and attach to ssb carb stone.
Monitor until manometer reads 12psi and then remove co2.

Problem: have not seen any change in manometer reading in 24 hours.
Above is the correct procedure. If you pressurize the headspace beforehand then little to no CO2 will flow through the stone.
 
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