[ndcube]

I don't think there could be any geometry effect at all, unless you were using an exceptionally tall and narrow fermenter.

Well, they are extremely worried about switching to cylindro-conicals in Belgium, due to the reduced ester profile from the taller tanks versus 1 to 1 height : width square fermenters.  Check out BLAM for more info on this.  CO2 inhibition from pressure is also scientifically documented in the commercial brewing world.

From the paper:
"If pressure is applied above 1 bar a formation of higher esters is visible. This
can also happen in tall fermentation vessels due to pressure. On the

Isn't this saying the opposite about pressure & esters.

Also, when homebrewing, won't using an airlock vs a non-sealed lid add pressure?
contrary, open or shallow vessels will give lower ester levels."

[hopfenundmalz]

Geometry may have some effect, but at homebrew volumes I don't worry about it.

My little 10 gallon batches in a cylindrical don't have the pressure diff top to bottom as a 800 barrel fermenter.

I have been covering the neck of the carboy with AL foil for the first part of fermentation.  When things slow down, I put on the airlock.

[narvin]

From the paper:
"If pressure is applied above 1 bar a formation of higher esters is visible. This
can also happen in tall fermentation vessels due to pressure.

Isn't this saying the opposite about pressure & esters.

Yes, that is the opposite of what I have heard -- that tall cylindro-conicals reduce ester formation.

http://www.scientificsocieties.org/JIB/papers/1992/1992_98_2_133.pdf

"The results of this study have confirmed that the formation of higher alcohols and acetate esters is inhibited by CO2 for all the yeast strains tested."