Carboy Trouble

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Sep 10, 2009
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If I am fermenting only 4 gallons of wine in a 5 gallon carboy, will the unoccupied space in the carboy cause a problem during fermentation?

I am assuming the unoccupied space is actually occupied by air. So is that going to ruin the wine?

Help. Thanks.
It being the primary is no problem. Once you rack and stabilize it then it will be a problem. I would rack into smaller containers like a 3 gallon carboy and a 1 gallon jug.
It's important to have the right sixe containers prior to making wine. Or, adjust the volume to what you have.
That is what I figured. What if I occupied the extra space by placing sterilized marbles or some other kind of object into the carboy? I read that idea on a different thread. Would that work?

Then that will be fine but would require lots of marbles to displace 1 gallon. You could go to a dump and get a few 1 gallon jugs for free as thats what Ive done. I have a bunch of these and also 3 liter jugs for when i make fruit wines and make extra for topping up after several rackings off the lees. You could even buy some gallon jugs with wine in them and drink them in the meantime! You also could inject an inert gas in there like argon or C02 or nitrogen like they sell at liquor stores for preserving a bottle of wine.
You could get a 3-gallon carboy and a 1-gallon jug.

This is just a theory, or just a idiotic idea but I'm going to throw it out here anyway.
Could we drop a small piece of dry ice into the carboy and let it sublimate before racking? This would ensure a dense sterile blanket of CO2 in the head space instead of air.
Hopefully someone more intelligent can help you out on this as I have no idea, the C02 part is good but I dont know if you can just drop it in your wine.
sorry I meant to say drop the dry ice into a empty carboy before racking the wine in. Since CO2 is heavier then air it should stay inside the carboy until it is displaced by the wine. With some additional thought, it maybe better to have the dry ice in a stocking or tie it to a string so it doesn't thermo crack the glass. And since dry ice is so cold, one may want to place a airlock onto the carboy, CO2 retention, and let the carboy get back to room temp before transferring the wine over.
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I think I'd pass on the dry ice. At least around here it would be cheaper just to get another carboy of the correct size as opposed to buying dry ice. I can see that freezing the wine as well. Radical temp changes like that aren't that good on wine. You want stability.
how would it freeze the wine? the dry ice would sublimate (convert from a solid to a gas) in a empty carboy. and as mentioned in my second post, "let the carboy come back to room temp before transferring wine".
I can get a 1 lb block of dry ice for around $2. If you can get carboys cheaper then that, let me know where your getting them from..
Sorry, misread your post. I thought you was wanting to submerge it into wine already in a carboy. Dry ice cost quite a bit more where I live. I see what you are talking about now.
dry ice

I was going to go down the dry ice route ... but I'm told that dry ice, in addition to producing CO2 ... also has a fair amount of debris embedded during the manufacturing process (ie not food grade conditions like regular ice).

Also, I could never figure out what to do with the remaining brick of dry ice ... you would only need a little piece to produce enough CO2 to protect a car boy or fermenting vessel.

You can't keep the dry ice in your regular freezer ... no where near cold enough to keep it.

So you would have to buy a big chunk, only use a little piece, and maybe add some unwanted junk into your vessel.
There was a suggestion of adding marbles in a nylon stocking into the carboy to displace the air space. I have a question about that. Does anyone know what the long term affects of leaving nylon leggings in a wine are? Should I bleach the stockings before to remove any dye that might be in them? What brands have people used?
You could also get a couple of 2 gallon carboys. Our local water supplier has water in two gallon glass containers (for the office water cooler) and mixing those with 1 gallon conatiners makes just about any number of gallons doable.

Sorry to drag up an old thread here but I had a thought to expand on the dry ice idea. What if one were to take an empty pop/water bottle and drill a hole in the cap to fit a racking hose snugly. Then slip the end of you racking hose into the hole in the bottle cap and put the other end of the hose with the cain hooked to it into the carboy. Now you would just have to put a chunk of dry ice in the pop bottle, put the lid with the hole and the racking hose running through it on the bottle and wait for the dry ice to evaporite and purge the air out of the carboy? Just make sure that there is no way that the pop bottle can ever build any pressure, that would be bad!
You can get a small tank of CO2, like the kind used for carbonation of beer and spritz some in there.
After degassing, I haven't worried too much since I use a mix stir and figuere the co2 released will just set on top of the wine and stay put under the airlock until I get to top up.

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