Sufficient fermentation head space?

[kohalajohn]

Is ample head space really a requirement for a fermenter vessel?

I have always assumed it is. we need lots of room for krausen and space for co2 above the krausen.

The reason I'm challenging this assumption is I have moved down to small batches in my serving kegs. I have moved away from my five gallon cornies and I have the 2.6 gallon steel kegs for serving and they are a delight in many ways. Easy to move, clean, and store in the fridge.

I still ferment in my relatively hard to clean 5 gallon corny kegs. They are only filled half way.

There is a 3.0 gallon stainless keg that I could buy for a fermenter. The convenience is tempting.

But is that tiny headspace enough? The difference between the 2.6 gallon serving keg and the 3.0 gallon fermenting keg is just a few inches of headspace. There would be times some krausen would spurt out the gas tube into the starsan bucket.

Well, lateral thinking here, maybe that's ok? What do you think? Do I need the big head room of a big five gallon fermenter?

 

[lumpher]

Needed headspace factors in malt fermentability, yeast, temp, if it was amply oxygenated, etc ... Using a 5g fermenter for 2.5 gallons or thereabouts is risky for contamination, as that's too much headspace. To get more to the point, you could use a blowoff tube in a 3 gallon for 2.5 gallons and that would be ok. I've always heard and read about 15% headspace is enough, but that's just a generalization.

 

[PCABrewing]

Is ample head space really a requirement for a fermenter vessel?

I have always assumed it is. we need lots of room for krausen and space for co2 above the krausen.

The reason I'm challenging this assumption is I have moved down to small batches in my serving kegs. I have moved away from my five gallon cornies and I have the 2.6 gallon steel kegs for serving and they are a delight in many ways. Easy to move, clean, and store in the fridge.

I still ferment in my relatively hard to clean 5 gallon corny kegs. They are only filled half way.

There is a 3.0 gallon stainless keg that I could buy for a fermenter. The convenience is tempting.

But is that tiny headspace enough? The difference between the 2.6 gallon serving keg and the 3.0 gallon fermenting keg is just a few inches of headspace. There would be times some krausen would spurt out the gas tube into the starsan bucket.

Well, lateral thinking here, maybe that's ok? What do you think? Do I need the big head room of a big five gallon fermenter?

I think five gallon would provide much more than needed but three seems like it may be borderline.
But who cares if you eject some foam into the blow-off bucket as long as it doesn't clog the hose?

 

[kohalajohn]

Yeah it wouldn't block the hose. That's the advantage of using a hose and a bucket.

I like to use the fermenter gas to purge a server keg, but that's not done until late in the fermentation, so foam should not be an issue by then.

I would much prefer to use a smaller keg. I think this gives me comfort that it's the right decision. So thanks

 

[brewmanStan]

Yeah it wouldn't block the hose. That's the advantage of using a hose and a bucket.

I like to use the fermenter gas to purge a server keg, but that's not done until late in the fermentation, so foam should not be an issue by then.

I would much prefer to use a smaller keg. I think this gives me comfort that it's the right decision. So thanks

Needed headspace factors in malt fermentability, yeast, temp, if it was amply oxygenated, etc ... Using a 5g fermenter for 2.5 gallons or thereabouts is risky for contamination, as that's too much headspace. To get more to the point, you could use a blowoff tube in a 3 gallon for 2.5 gallons and that would be ok. I've always heard and read about 15% headspace is enough, but that's just a generalization.

 

[brewmanStan]

I've been wondering about this myself. I have plastic 5 gallon big mouth fermenters that I've been using to make four gallon batches. The headspace hasn't caused me any problems in the thirty or so batches I've made like this thus far. I would really like to go down to three gallons and still use the big mouth fermenters to cut down on the weight I have to carry downstairs, but as someone stated here, that may be pushing it. I've got 3 gal glass fermenters but when full they still weigh about as much as four gallons in the plastic big mouth fermenters, which kills my reason to go to 3 gallons. Not to mention the glass fermenters are much more of a pain in the a#* to clean!

 

[kohalajohn]

Yeah, it's interesting. The progression does seem to be folk moving to three gallon brewing. I see the grain kit delivery sites now offer three gallon as well as five gallon delivery kits.

I think it's because as home brewers we are no longer college kids hanging out on a Sunday and consuming ten gallons all at once.

Also I see a lot of sites selling these 2.6 gallon version of a corny keg.

But what about the fermenter?

I was just looking at a three gallon steel corny keg. But it's $180. I removed it from the shipping cart, as that's too much money, when my exising old five gallon cornies are fermenting just fine.

Now I'm wondering about a seventy dollar kegland All Rounder. Excellent value.

Now, at thirty liters its even bigger than my old twenty liter cornies. But the you tube videos show it fermenting when only half full. I don't think excesssive head space is a problem as long as you keep things clean and pitch at a good rate. And you can pressurize this one, which keeps the bugs out.

It has a huge mouth, is wide instead of tall, and is transparent, so cleaning should be easier. And it would be fun to see the fermentation again. I will certainly not go back to glass. But I would like to see the magic happen. And these new modern plastics seem to be impressive.

 

[kohalajohn]

@brewmanStan have a look at those All Rounders and please share your thoughts.

I had an aversion to plastic, but I think this modern plastic seems to be a different thing.

 

[brewmanStan]

@brewmanStan have a look at those All Rounders and please share your thoughts.

I had an aversion to plastic, but I think this modern plastic seems to be a different thing.

Hey kohalajohn. Thanks for pointing out the All Rounder to me. I've seen them before but never paid much attention to them. I don't have any reservations about the type of plastic used in these modern vessels. I once did, but that has faded after five or six years of using the 5 gal big mouth fermenters. They are sooooo much easier to clean, and I'm pretty continence about cleaning and sanitizing before fermenting. I run a vent tube into a large jar of StarSan solution during the fermenting process so it's pretty well sealed from the outside world. I once had a tube blow out of the solution but I got lucky and found it early and nothing bad became of that batch. After that, I now secure the tubes where they can't blow out. I want to try 3 gal but I can't make myself do it yet. Too much work and expense to have it go to s*%t.

 

[kohalajohn]

Stan, I think you'll enjoy three gallon. If you choose. It's fun to split a batch in half and make two at the same time. You can alter an ingredient in one batch and then find out what you prefer in the end.

In kitchen food cooking we can taste a soup as we go, and with real time feedback we can add salt etc. But when I make a certain recipe in January and then make it again in June, too much time has gone by for me to remember how a variation in ingredeients made a difference, and which I may prefer.

But when you have two sister brews come online at the same time, you can compare in real time, just like in food cooking, and realize that "oh my god, in batch #2, adding all the flavour hops at flameout is much much more the way I like it"

 

[Broken Crow]

While I don't think the headspace in a half-filled 5G keg is a big deal, if you wanna downsize your fermenter there are a number of options;
1/ 3G Fermonster https://www.ontariobeerkegs.com/fermonster-3gal-pet-carboy.html with the modded ball lock/floating diptube lid https://www.homebrewtalk.com/thread...lete-closed-transfer-system-for-cheap.680992/ ..this can hold about 3psi or so which is more than adequate for pushing sanitizer out of keg, plenty on here do it and I've done it myself.
2/ Milk Can. Available in many sizes and championed on here by our dearly departed @bracconiere who reports it to hold 5psi ok; https://www.homebrewtalk.com/thread...il-for-you-today.337763/page-269#post-9207901 ..here's a pic of it in a silly thread; https://www.homebrewtalk.com/threads/this-site-is-dumb.701897/#post-9300472
..if you do wanna try one out, look for one with a flat lid that you can easily install bulheads in.
3/ Other Stainless Steel items such as this food/oil/whatever gasketed 12L cannister: https://www.amazon.ca/dp/B0DGF9B6KY...d5c19&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw&th=1 ..plenty of room on that to hold not just ball lock bulkheads, but you could a separate ball-valve for blowoff during high-krausen so you don't gunk up your gas post.
Just throwin some ideas...hope they might be some food for thought.

 

[wickedbeernut]

But is that tiny headspace enough? The difference between the 2.6 gallon serving keg and the 3.0 gallon fermenting keg is just a few inches of headspace. There would be times some krausen would spurt out the gas tube into the starsan bucket.

A custom corny lid like this would allow for a larger blow-off pipe. You could even leverage a 1.5" tri-clamp spunding valve, carbonating in the fermenting keg before transferring (under pressure) to the serving keg. The possibilities are endless.

.

 

[hungupdown]

The krausen bubbles can carry a fair amount of liquid.

In overflows, I've lost around 2L of a 20L 15% stout, and 3L of a 23L 8% stout, from a 30L vessel.
Having a blow off tube, means loss doesn't cause a mess.

I now give stouts 100% headroom.

 

[brewmanStan]

While I don't think the headspace in a half-filled 5G keg is a big deal, if you wanna downsize your fermenter there are a number of options;
1/ 3G Fermonster https://www.ontariobeerkegs.com/fermonster-3gal-pet-carboy.html with the modded ball lock/floating diptube lid https://www.homebrewtalk.com/thread...lete-closed-transfer-system-for-cheap.680992/ ..this can hold about 3psi or so which is more than adequate for pushing sanitizer out of keg, plenty on here do it and I've done it myself.
2/ Milk Can. Available in many sizes and championed on here by our dearly departed @bracconiere who reports it to hold 5psi ok; https://www.homebrewtalk.com/thread...il-for-you-today.337763/page-269#post-9207901 ..here's a pic of it in a silly thread; https://www.homebrewtalk.com/threads/this-site-is-dumb.701897/#post-9300472
..if you do wanna try one out, look for one with a flat lid that you can easily install bulheads in.
3/ Other Stainless Steel items such as this food/oil/whatever gasketed 12L cannister: https://www.amazon.ca/dp/B0DGF9B6KY...d5c19&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw&th=1 ..plenty of room on that to hold not just ball lock bulkheads, but you could a separate ball-valve for blowoff during high-krausen so you don't gunk up your gas post.
Just throwin some ideas...hope they might be some food for thought.

Thanks Broken Crow. I'm of the opinion, and maybe you also, that if I keep everything good and clean and sanitized I should be alright with 3 gal in a 5 gal fermenter. I don't ever open my fermenters before at least 18 days using US-05 so the chance of contamination is low, and generally the yeast is always through working by then anyway @ 65-68F. Just something I started doing 5 or 6 years ago with no problems.

 

[kohalajohn]

Thanks @Broken Crow

I had been looking at this three gallon one, but the price was too high.

But today I got lucky at my homebrew shop. I was there to pick up some grain kits.

Today in the shop guess what, there was a used version for $99 cdn. Holds pressure, all checked out by my trusted store owner.

It's home soaking right now.