Head Space in Primary?

[J-Dewey_1980]

I have only ever used the 7 gallon primary buckets and racked to 6 gallon carboys, but was recently gifted some 2 gallon fermenting buckets and one gallon carboys. I know some folks do primary under airlock and some do not, so I am not sure how that factors here, but my question is if I want to just ferment a gallon of must to then rack into a one gallon carboy, can I just put a gallon into a 2 gallon bucket (with airlock), or is that way too much headspace for primary? I appreciate any suggestions.

 

[winemaker81]

Headspace is not a problem in primary. The must is outgassing CO2 enough that it's useful to stir the must 1 to 4 times daily to introduce O2. Yeast needs O2 for reproduction, which is why fermenting wine in a closed container is not recommended.

O2 is yeast's friend but it's wine's enemy. Post fermentation is when headspace is a concern.

 

[J-Dewey_1980]

Thanks for the fast reply. Since you don't fermet under airlock, do you just cover with a towel or how do you prefer to do that step in primary?

 

[winemaker81]

Thanks for the fast reply. Since you don't fermet under airlock, do you just cover with a towel or how do you prefer to do that step in primary?

Happy to help!

I use towels over the primaries.

 

[Rice_Guy]

The general rule is that yeast are actively producing biomass in the first third of sugar reduction (1.090 down to 1.050) and need oxygen or else create off flavors (reductive sulfur). If you do a mead the recipe may be under airlock and also say whip some oxygen in before 1.050 to encourage yeast reproduction. Many whites and fruit wines are under airlock after 1.050, ,,, or when then stop making foam. Reds frequently have skins which would mold if not mixed, ,,, so when solids are filtered is appropriate.