How full does carboy need to be?

First time brewing. I transfered the beer to the carboy a couple of days ago. I showed the pic that you see here to a coworker and he told me that there should be very litter air in the carboy and that I should boil some water and fill it up the rest of the way. I did that and now I wonder if I should have. I see pics of carboys on here and none of them are as full as I made mine. I'm not worried that it will hurt anything, just wondering if it was necessary. BTW, he told me that the reason is all that air contains oxygen which is bad.
Thanks in advance.
I guess I'm not allowed to post a pic.??? Anyhow, there was about a gallon or more of air in carboy. Now there is about 2 oz.

I dont know about what you co worker said, but I hear aiming for 5 to 5.5 gallons is what most shoot for. From my 4 batches under my belt , I've had aggressive fermentation that required a blow off tube on all 4. That was in a 6 gallon bucket and 6 gallon better bottle. . I hear that in secondary, you try to rack to a carboy with very little head space.. but I dont ever plan on doing a secondary so I cant comment. I's sure it will be fine, but you might want to post specifics on what you brewed and size of you carboy so the experts can comment. one thing to add fermentation will be very active, you wont have to worry about oxygen when its active, the co2 will displace it rather quickly. Make sure you have a blow off tube in place, especially if you carboy is maxed out.

You can post a picture! You can host it someplace like photobucket or flicker, and then post the pix here.

Well, it's too late now, but your coworker was wrong.

Not entirely wrong, though. In wine, that is correct. You want to minimize headspace. And in some beers that will be aged a long time, you want to minimize headspace. But in the vast majority of beers, there is no need to top up with water- and in fact you just watered down your perfectly good beer.

When you rack the beer to secondary, if you are careful and don't splash it, there is minimal chance of oxidation. In addition, some co2 is knocked out of suspension, and will come out of the beer. Since it's heavier than o2, it'll form a "blanket" over the beer to help protect it. If you were going to be aging that beer for many months, it would probably need to be in a smaller carboy. But for several weeks or even a month or two, it would have been fine.

so, for now, just accept some slightly watered down beer. It'll still be good, and it'll still be beer. Next time someone gives you advice, just smile and nod, and then look it up yourself!

and welcome to HBT!

Wow, that was quick. Thanks guys. Now I know for next time. By the way, I used a "Brew House" kit. It doesn't say or even give a range of the expected alcohol content. What should I expect (That is, before I watered it down)?

TMRBeer said:

Wow, that was quick. Thanks guys. Now I know for next time. By the way, I used a "Brew House" kit. It doesn't say or even give a range of the expected alcohol content. What should I expect (That is, before I watered it down)?

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Did you take gravity readings? If so, you can calculate the approximate alcohol content knowing your starting and finishing gravities. If you didn't take them, they might be listed in your instructions. Failing that, if you post the receipe, someone might be able to estimate it, knowing the potential sugar in your ingredients. Don't look at me though, I'm not that smart (yet)

so i'm curious .... is he gonna need a blow off tube now? he said "transferred to a carboy", i'd assume from a bucket? but ... just curious

Yes Nanik, I transfered to the carboy from a bucket. I waited until after the foam subsided, about 3 days before the transfer. I don't think I need a blowoff tube anymore, as there was essentially no foam after the transfer. I have an airlock with rubber stopper on top and it is half filled with water.
I had a reading of 1.012 when I transfered it to the carboy, which seems like pretty low alcohol content. But, that was day three. How much more should I expect alcohol to increase?
Thanks again.

TMRBeer said:

How much more should I expect alcohol to increase?
Thanks again.

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None at all- at 1.012 it was probably done. Then, you watered it down, so you might have actually decreased the alcohol pretty significantly, depending on how much water you added. If you added a gallon of water to a beer that was, say 5% ABV, then you watered it down to 3.6% ABV.

If you know your original gravity, we can do the math though and let you know for sure.

TMRBeer said:

I had a reading of 1.012 when I transfered it to the carboy, which seems like pretty low alcohol content. But, that was day three. How much more should I expect alcohol to increase?
Thanks again.

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Actually a low number is good. Gravity is a measure of the density of the beer, basically you are measuring how much sugar is in the beer. The original or starting gravity is high, then as the sugar is converted to alcohol, the gravity will drop. IIRC water has a gravity of 1.000, so that 1.012 means there is some residual sugar sugar left (probably unfermentables).

The calc to estimate alcohol by volume is (OG - FG) * 131 = ABV%

-kap

there's a saying in utah regarding the beer...three-two.

i guess that's why wyoming was invented!

Ok - (OG - FG) X 131 =
(1.060-1.012) X 131 = 6.288% Then I added about a gallon of water - so probably a bit over 4%. I'm OK with that.

kaplanfx said:

Actually a low number is good. Gravity is a measure of the density of the beer, basically you are measuring how much sugar is in the beer. The original or starting gravity is high, then as the sugar is converted to alcohol, the gravity will drop. IIRC water has a gravity of 1.000, so that 1.012 means there is some residual sugar sugar left (probably unfermentables).

The calc to estimate alcohol by volume is (OG - FG) * 131 = ABV%

-kap

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The formula to calculate the ABV is the OG-FG X 105. According to Mr. Papazian, page 43 in "The Bible".

brownsbrew said:

The formula to calculate the ABV is the OG-FG X 105. According to Mr. Papazian, page 43 in "The Bible".

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this is the best explanation of find alcohol by volume i've found ... its where i came up with my equation

HowStuffWorks "How do brewers measure the alcohol in beer?"

the equation i use is

[(OG – FG) * 1.05] / FG = Alcohol By Mass (ABM)
ABM / 0.79 = Alcohol By Volume (ABV)