Fermentation head space? How much?

I've started my very first batch of cider, in a 3 gallon carboy. I have a commercial stopper and airlock, and two questions.

1 - how much headspace is required for primary fermentation in a glass carboy? I left just a few inches.

2 - when installing the airlock, how much water are you supposed to add to the airlock? does it have to be sanitary water/vodka?

Thanks

1. It varies. Sometimes you can get away with very little depending on yeast and temperature and other times you need more. I had a 5 gallon batch of apfelwein almost overwhelm a 7.9 gallon bucket. Certain yeast strains can be done with mere inches, I forget which ones though.

2. Sanitized water (Idophore, starsan etc) or some good cheap 80proof works too. Just enough to prevent air fro coming back in and a enough to be good for a few days without it evaporating. Make sure you keep an eye on it. Also temperature changes will cause it to suck back into the carboy sometimes, 80proof is my preferred choice over starsan.

#2 is pretty well answered by SwampassJ. My $0.02 for 1 based on my experience is that as long as whatever you are fermenting in has a good seal you will be ok. I have done many 3 gal batches in 6 gal carboys and have not lost one yet. At the start I used to blast them with Co2 from my keezer but lately I just let em go. Just remember to keep a good seal once it gets going.

I'm looking at a 6 gallon batch right now, and hoping it'll fit in a 6.5 gallon carboy with California ale yeast. Temp will be something around 68F-70F. Any thoughts on if it'll be okay?

I've always had more than enough space with 5 gallon batches, but 6 gallons makes me a little nervous.

I would use a blowoff tube just in case. I typically don't get as vigorous of a fermentation with cider as I do with beer, but at those temps it could get messy with only a half gallon of headspace.

TheBrewWarrior said:

I'm looking at a 6 gallon batch right now, and hoping it'll fit in a 6.5 gallon carboy with California ale yeast. Temp will be something around 68F-70F. Any thoughts on if it'll be okay?

I've always had more than enough space with 5 gallon batches, but 6 gallons makes me a little nervous.

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This sounds like blow off country.

I use WLP 775 and very little head space needed.

But CA Ale...... ? If it were a beer i'd say not enough head space. Especially at those temps.

wadefisher said:

This sounds like blow off country.

I use WLP 775 and very little head space needed.

But CA Ale...... ? If it were a beer i'd say not enough head space. Especially at those temps.

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Ended up only putting in 5.5 gallons in the 6.5, and it looks okay so far. I've never used a blow off before. I'm gonna run to the store today, and get the tubing and such. Thanks for the advice.

The bottom portion of a 3 piece airlock works well to attach the tubing to. Then it fits into a normal bung. I've seen and always thought it was a good idea to use large tubing (2"?) and just poke it into the top of the carboy. It fits tight and that way even if there's excessive pressure nothing...pops off.

With about 5.5 gallons of wort in a 6.5 gallon carboy at temps from 66 to 68 (weather ended up going cold again, which was a plus!), there was plenty of head space. Beer should be about 5.8% to 6% ABV.

Everything looks great, but I'll definitely use a blow off the next time I do a batch larger than 5, just to be safe. Thanks for the help.