Headspace for the start of a solera project?

I brewed up 5.5 gallons of a sour red ale base last week and pitched US-05 for primary. Once primary fermentation dies down I'm going to transfer to a glass carboy for long term aging and the start of a solera project.

I have 1 gallon of yeast/bacteria built up from a previous sour that I plan on using to inoculate the solera after primary fermentation is complete.

My question is this:

I have a 5 gallon carboy and a 6.5 gallon carboy that are both empty right now. After racking the red ale I'll have about 5 gallons after trub loss.

With the 5 gallons + 1 gallon of starter at my disposal should I....

1) Add it to the 6.5 gallon carboy even though there will be a gallon of headspace? This will let me pull and brew slightly larger batches in the future.

2) Add it to the 5 gallon carboy, filling completely to the neck, thus eliminating headspace.

I plan on aging this for at least 8 months before pulling 3 gallons to age on some sort of fruit and topping up with another fresh 3 gallons.

Any advice?

Both of those options are fine. I know too much headspace can be bad for a beer, especially a sour beer, but I think that might be a little overstated. I have two soleras going and I don't worry too much about headspace. My theory is that the yeast/bacteria/brett is always slowing working and creating co2, mixing with any oxygen. Also, if oxygen gets in usually a pellicle forms to protect the beer. Good luck!

-Mike

You could whip up a gallon from extract, and essentially step up the gallon of sour starter with that gallon of new wort. You could do that in your 6.5 gal carboy, then after its mostly torn through, top off to the neck with your 5 gal of red.

CO2 is heavier than oxygen so the headspace is not an issue.

edwardgriffin said:

CO2 is heavier than oxygen so the headspace is not an issue.

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No. just no.

Just to update -- I racked the beer onto the yeast/bug blend in the 6.5 gallon carboy about 10 days ago. The belgian / wild yeasts starting eating away pretty viciously at the residual sugars that US-05 left behind and I had a violet fermentation for about 5 days which caused quite a bit of gas and beer to spray out of the airlock. I'm just leaving it alone and won't remove the airlock for at least 5-6 months before doing any sampling.

TAK said:

No. just no.

Click to expand...

http://beersmith.com/blog/2015/06/18/why-oxygen-is-bad-in-your-home-brewed-beer/

"Once fermentation is complete, a layer of carbon dioxide, which is heavier than air, sits above the beer and provides a protective layer in your fermenter. If you don’t disturb the beer, that layer does a good job of protecting your beer as it ages."

Since he is adding yeast which should rebuild that protective layer, how is the headspace of a 6.5 gallon carboy going to be an issue?

The internet never lies! Thanks for the link.

edwardgriffin said:

http://beersmith.com/blog/2015/06/18/why-oxygen-is-bad-in-your-home-brewed-beer/

"Once fermentation is complete, a layer of carbon dioxide, which is heavier than air, sits above the beer and provides a protective layer in your fermenter. If you don’t disturb the beer, that layer does a good job of protecting your beer as it ages."

Since he is adding yeast which should rebuild that protective layer, how is the headspace of a 6.5 gallon carboy going to be an issue?

Click to expand...

This line of thinking completely ignores that fact that gasses will mix together, not stratify. Sure, there will be co2, but o2 ingress through permeable materials will occur. That is why having a topped up fermentor is important, because it will decrease the surface area of the beer exposed to any o2. In the short term, the ingress is negligible so the co2 blanket theory holds true, but on a long timeline, the o2 content becomes a factor to consider.

Elduder said:

This line of thinking completely ignores that fact that gasses will mix together, not stratify. Sure, there will be co2, but o2 ingress through permeable materials will occur. That is why having a topped up fermentor is important, because it will decrease the surface area of the beer exposed to any o2. In the short term, the ingress is negligible so the co2 blanket theory holds true, but on a long timeline, the o2 content becomes a factor to consider.

Click to expand...

That makes sense to me. Glass being preferable since it is not permeable. I guess the key is knowing what constitutes short term and long term. In the case of the OP, 8 would be long term.

I read the same blanket rationale in relation to the fast fermenter. #1, it's an 8 gallon container, which is a lot of headspace for a 5 gallon batch. #2 the yeast and some liquid is removed after fermentation, which increases the headspace. #3 when the ball is reattached, it has additional air that has to make it way up to the top again.

http://www.fastbrewing.com/products/fastferment

Thanks for an intelligent reply. Always nice to have a brewer willing to help another hone his knowledge.

https://www.homebrewtalk.com/showthread.php?t=597605

The debate continues with an 8 year old batch.