Can you bottle half a 5 gal batch(carboy size?)

Can you bottle half a 5 gallon batch and put the other half into secondary if the secondary container is a 5 gallon carboy.
in other words will i run into any trouble with oxidation or anything by having my secondary fermentor being half full with beer and half full with air?

i want to add some flavors to the second half so i can taste the differences between two exact batches

Totally fine.

Just remember to account for less priming sugar. If it is truly half then you can cut what you normally use in half. There are also priming calculators out there.

you should be fine. just make sure you put an airlock or blowoff on it.

If you want to do this frequently, you should get a 3 gallon carboy. It's the right tool for the job.

if you are worried about oxygen, i think it's the diameter of the side of the beer exposed to atmosphere, not the height of the container interior. if you have a six inch cylinder four foot long, filled to the top, you have the same exposure as one filled halfway. if you were full up to the neck, then you will have more o2 exposure now that your diameter has increased as your level has dropped, but my experience has been that it's okay. i use oversized carboys and even large diameter glass jars with no issues. if you are really worried purge w co2 or argon or pour a little seltzer onto the top...

spearko520 said:

i think it's the diameter of the side of the beer exposed to atmosphere, not the height of the container interior. if you have a six inch cylinder four foot long, filled to the top, you have the same exposure as one filled halfway.

Click to expand...

The diameter (or, really, the surface area) exposed will affect the rate of oxidation. The volume of head space (so surface area times empty height) will affect the total amount of oxidation that can occur, since there will be more oxygen available for reaction. This is assuming that there is no flow of fresh air in through the airlock.

so what you guys are saying is the surface area of the liquid(based on the diameter of the vessel) will affect the rate of oxidation. the height will affect how much oxygen is available. but since the beer is usually filling the headspace with co2 and no new air is getting in. and since fermentation is pretty much done and there is much more oxygen available to invade the beer won't this cause a problem?

suzanneb said:

so what you guys are saying is the surface area of the liquid(based on the diameter of the vessel) will affect the rate of oxidation. the height will affect how much oxygen is available. but since the beer is usually filling the headspace with co2 and no new air is getting in. and since fermentation is pretty much done and there is much more oxygen available to invade the beer won't this cause a problem?

Click to expand...

you could always purge it with CO2 first if you have that available.

suzanneb said:

so what you guys are saying is the surface area of the liquid(based on the diameter of the vessel) will affect the rate of oxidation. the height will affect how much oxygen is available. but since the beer is usually filling the headspace with co2 and no new air is getting in. and since fermentation is pretty much done and there is much more oxygen available to invade the beer won't this cause a problem?

Click to expand...

During active fermentation, CO2 will be produced and will displace O2, so it's really not an issue. You'll have some protection after fermentation is mostly done because there's still CO2 in solution that will outgas, but eventually you run out of protection. So once fermentation is done, if you're worried about oxidation, you need to take steps to prevent it---the beer can no longer protect itself. The easiest way is to fill the carboy all the way up to minimize both exposed area and reduce the head space volume to a negligible amount. If you can't do that, then adding a neutral blanket (CO2 or N2, or I've heard reports of food grade mineral oil being used, but I really wouldn't go there) is an alternative.

Note that, for all the talk of a CO2 blanket forming, that's not really quite how it works. Unless the beer produces/releases enough CO2 to displace all the air in the headspace, the CO2 it does produce will mix quite thoroughly in there, so you'll get oxygen exposure. When it produces a huge amount of CO2 at the beginning, it mixes as well, but it's continually pushing the mixed air out, so the concentration quickly tends toward pure CO2. If you put a blanket in, you've then got to put your airlock on to keep it in place.

Finally, let me just say that I'm a n00b, so I'm not necessarily saying you will or won't have a problem with oxidation. So you may be fine just letting it ride, my advice is aimed at taking the best action if you decide that you're worried about oxidation in the first place.

I will say that it is not fine and that you will most likely run into oxygenation issues.

Putting 2.5 gallons of wort in a 5 or 6 gallon carboy to ferment is fine; it will actually create a richer, denser C02 blanket than 5 gallons in a 6 gallon carboy... which is a good thing.

However, putting 2.5 gallons of beer in a 5 or 6 gallon carboy to condition is not fine. That C02 blanket you worked so hard to achieve is gone and replaced with 2.5-3.5 gallons of empty air space.

Take HomebrewMTB's advice and get yourself a 3 gallon secondary.

i have a 3 gal secondary but it is full of something else.
i don't have co2 tank so is there anything else i can do.
can you really add seltzer?
is there any other way to fill with co2?

You have four choices...

1st choice - 3 gallon keg
2nd choice - keg with CO2 filled headspace
3rd choice - Wait until one of the above two are available
4th choice - oxidized beer

seltzer is carbonated water. only. don't add a lot and when the co2 in the seltzer comes out of solution it should make a little blanket. the beer will be a little watered down. You don't have to use co2 either. you can use any inert gas. argon or nitrogen will work, too. My experience is that oxidized beer doesn't usually happen as long as you use good transfer processes, regardless of the container. i use wood stoppers, bunged barrels, and tin foil, in lieu of airlocks. some of it depends on the length of time you're dealing with, too. usually the rack, or what you rack it onto, stirs up a bit of activity, anyway- so you have co2 coming out of the liquid.

You could get a **PLASTIC** bottle (or a bucket fermenter with a lid) and some dry ice. Rig an airtight hose from the cap of the bottle/lid into the carboy with the beer, put the dry ice in the empty bottle/bucket and add a little water. Close it up and it should spew CO2. I'd keep a close eye on it to make sure it doesn't ice up the hose and burst the container (DO NOT use glass containers for this).

I've not actually tried this, but was considering it for purging a mead. If you can get pure dry ice, you could perhaps add it right to the beer, but it's easier to get ahold of the regular stuff. You don't want that getting in your food.

The idea of a CO2 blanket is a bit of a fallacy. Unless you dump a ton of seltzer in, your little blanket will mix with the rest of the air fairly quickly.

you could prime the entire beer batch as usual, bottle half, and put the primed second half into the 5-gal carboy. the yeast in the second half will digest the sugar and release CO2.

some people regularly add a bit of boiled sugar (like an ounce or two) to the secondary vessel before racking to in, so that it gets mixed in to the beer and creates some CO2. others think this practice is unecessary.