Volume loss in primary??

Anyone else noticed this? I'm not talking about trub build up. I'm talking about the overall volume of both wort/beer and trub before and after primary fermentation.

I've got volume markings on my carboy, and I've noticed at least a 1 qt loss in volume with my last two batches. No liquid's coming out of the airlock, so that's not it. I do get some yeast stuck to the dome of the carboy, but it can't account for a qt of volume. I'm at a loss. Does the wort become more dense as it ferments?

Evaporation, CO2 expulsion, krausen stuck to the sides, etc all contribute to a slight volume loss during fermentation.

Fermentation increases temp. When the temp drops the volume will decrease also.

Yuri_Rage said:

Evaporation, CO2 expulsion, krausen stuck to the sides, etc all contribute to a slight volume loss during fermentation.

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I'll buy that. But it sure seems like much more than I would have thought.

orfy said:

Fermentation increases temp. When the temp drops the volume will decrease also.

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That may be true, but that's not what I'm seeing. My CFC cools my beer to 65 deg, so I'm pitching a few degrees cooler than the temp when it's done fermenting.

I also did a little research on the density idea. Actually beer is less dense after fermenting, not more dense. Hydrometer readings are really measurements of the density relative to water, and the reading is of course lower after fermentation, thus less dense.

Anyway, it was just the first time I had ever noticed the decrease in volume and thought it interesting and worth discussion.

Cheers!