Is dry ice "clean"?

Here's the story: I have a 2.5-gallon batch going in a 6-gallon carboy (because I am too cheap to buy 3-gallon carboys when I have these perfectly good 6 gallon ones). I am overdue to rack it into secondary (another 6-gal) for dry hops.

Now I figure it was probably fine to do the primary in a huge carboy since the yeast action would quickly purge the oxygen from the container. However, I am worried about what will happen in the secondary with a carboy full of air.

I don't have a CO2 system, so I had this idea to get some dry ice and drop a piece in the empty secondary until it has completely sublimated, thus filling the carboy with CO2 before I add the beer. Good idea or bad idea? Is dry ice pure CO2 or are there any contaminants? Of course I would not plug the carboy while the dry ice was in there.

Then I would use the rest of the dry ice to help chill another batch on the same day (outside in a tub of water).

Thoughts?

I have never tried using dry ice before but I read somewhere on here that there is oil from producing it on the dry ice. I can't see anything living on it because it is so cold. You could get some and put it in a bowl and see if anything is left behind after it melts

I think I read of this being done successfully, though I'd be just a bit concerned about the integrity of a glass carboy being tested by the spot thermal shock under the dry ice.

As for contamination, I'd think there'd be very little that could survive the surface temperature of dry ice, and what did would then have to survive the alcohol in your young beer. I wouldn't be worried about all that...

Cheers!

Just dry hop in the primary.

Or put the dry ice in a different container that is connected to Carboy cap with tubing. Pressure would build in small one and displace o2 in Carboy.

JonM said:

Just dry hop in the primary.

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+1 I've moved to dry hopping in the primary unless I want to harvest yeast.

jonm said:

just dry hop in the primary.

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+1

JonM said:

Just dry hop in the primary.

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It has been in primary for over 3 weeks now, so I kind of wanted to get it off the sediment (not because I am paranoid about autolysis, but more because I like to use the secondary as an opportunity to get a clear look at the beer-in-progress). And I did kind of want to try harvesting some yeast (love that SDSY), although I wouldn't be devastated if that didn't work out.

I like the idea of piping in the CO2 from the dry ice in a separate container. Then I could even add some water (maybe even StarSan for paranoia's sake!) to the DI to make it sublimate faster. Maybe a (clean) LDPE milk jug?

I guess another idea would be to start an apfelwein or something and tube the outgassing into my carboy! Roughly the same cost as dry ice, but then in 4 months I'll have some apfelwein AND a free 1-gallon jug as by-products

If you are going to pipe it in just use baking soda and citric acid to form CO2.

Hmmm, would distilled vinegar work for that? I can't help but think that it would cause bad flavors; maybe citric acid wouldn't have that problem? I don't have any citric acid on hand, though.

chocotaco said:

Hmmm, would distilled vinegar work for that? I can't help but think that it would cause bad flavors; maybe citric acid wouldn't have that problem? I don't have any citric acid on hand, though.

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I was thinking vinegar might be problematic but would produce CO2. You can get citric acid at a grocery store in the cooking/baking/spice section. It is very common and inexpensive.

I would not use dry ice to do this, the chance of shattering the carboy from the pressure buildup would worry me more than the possible contamination.

I would consider using the seperate container and connect it to the carboy then drop the dry ice and a small amount of water to create the reaction you are looking for.

I have not done this but the theory is sound so long as it is pure co2 being produced and doesn't carry anything to produce off flavors during the process.

Ok so my chemistry might not be sound.


From googling dry ice I think it is just co2 that is cool to its solid state. There maybe traces of oils that would not transfer. That being said, the equation would look like this

H2O+CO2--->H2CO3

So carbonic acid would also be released. Sanitizing the new bottle and killing any contaminants?

Still think it would work as long as to much pressure was never built.

I've done this, and it works fine. Plastic is safer than glass, and there is no risk of pressure build up unless you plug the top. The biggest worry is the extreme cold sitting in one spot on a glass carboy, as others mentioned.

You can get around this by sublimating in a small volume of preboiled water in the carboy, or sublimating in a different container and "piping" the gas in, as others have mentioned.

There are no contaminants growing in/on dry ice, and no oils. Also the only equation you would be using is:
CO2(s) --> CO2(g)

A teensy amount of Carbonic acid will be produced as an intermediate, but will decompose into CO2 almost instantly with water present . There will be no sanitizing action.

Awesome. Thank u. My chemistry seemed wrong.

I have a new idea - since I have a carboy mostly full of CO2 (the primary), what if I just use my autosiphon to pump some of it into the secondary? Since CO2 is heavier than air, would it form a nice little blanket to rack my beer underneath? Or would it just mix with the air in there?

It would mix.

Think about how carefully you have to pour a black-and-tan. Then, think about how much better liquids are at "staying put" than gasses.

The only reason the "CO2 blanket" works is because you're releasing several times the container's volume of CO2, and leaving the container still for days at a time.

ColoHox said:

There are no contaminants growing in/on dry ice, and no oils.

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My understanding is that if you do not buy food grade dry ice there may be contaminants. Whether oil or what I do not know.

Companies specifically sell food grade dry ice. Make sure you buy that.

http://www.continentalcarbonic.com/food-grade-dry-ice.html

Update: I decided to do the simple, obvious thing and buy a 3 gallon carboy.

Put a coffee filter in a funnel put the funnel in the carboy the co2 will pour in like liquid, the coffee filter will absorb, said "oils" as well as stop the small piece of co2 falling and causing said "thermal spot shock" and by the by products of base and acid reaction are hydrogen, dihydrogen oxide, and salt, don't think ya want salt in ya beer. hope it helps

chocotaco said:

Update: I decided to do the simple, obvious thing and buy a 3 gallon carboy.

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I have a bunch of those and they're great for test batches, split batches to experiment with yeasts (eg, brew a stout and do 1/2 with 1272 and 1/2 with Denny's Fav 50), and, of course, for bulk aging 3-gallon batches. Cheers!

And they're good for big ol' lager starters too.

Whsoj said:

the by products of base and acid reaction are hydrogen, dihydrogen oxide, and salt, don't think ya want salt in ya beer. hope it helps

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What acid/base reaction are you talking about? There is no salt, and by dihydrogen oxide...do you mean water?

JonM said:

I have a bunch of those and they're great for test batches, split batches to experiment with yeasts (eg, brew a stout and do 1/2 with 1272 and 1/2 with Denny's Fav 50), and, of course, for bulk aging 3-gallon batches. Cheers!

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Yeah, I had already decided I want to start doing 2.5 gallon batches exclusively because
1) I can brew more often for the same ingredient costs and gain more experience as a brewer
2) I can BIAB all-grain batches without buying a larger kettle
3) In the event that I seriously screw up a batch, I lose a smaller amount of investment in the ingredients
4) I would not be able to drink the requisite amount of beer to keep brewing 5 gallon batches at the pace I want to brew them
5) I can brew a greater variety of different beers to improve my breadth as a beer drinker as well

So it makes sense for me to invest in the equipment to do so. I tried to find someone to trade me 3-gallon for my 6-gallon but couldn't find any takers, so I tried to make do with the larger ones without thinking it all the way through until I already had a batch in primary.

But I guess I can just relegate them to the attic and maybe someday I will scale back up.

It's hard to be a cheap-ass spendthrift and also be a homebrewer, that's for sure!

Someday your brew area will look like this!

ColoHox said:

What acid/base reaction are you talking about? There is no salt, and by dihydrogen oxide...do you mean water?

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Yes H2O water is what I meant, and sodium acetate co2 and hydrogen are created sodium acetate is left in powder form in the bottom its salty because of the sodium in sodium bicarbonate.