Beer Loss To Blow Off

[brewerjimbo]

I have a question regarding inexplicable cellar loss in a batch of beer. Is it possible to lose a statistically significant amount of beer (8-14%) due to excessive blow off? This happened in a slightly overfilled 60 bbl cylindroconical fermenter with approximately 13% freeboard. The original gravity was fairly high and the blow off lasted for at least 2-3 days. Has anyone else experienced excessive losses due to overfilled tanks or vigorous blow off? Thank you.

[grnis]

13% doesn't leave much headspace.

25% is the recommended head space for lagers in combitanks.

For ales, 30-40%.

Can you try adding some antifoam and see if the problem disappears or is reduced?