I think I’m ok but I’m worried about possible oxidation. If I brew a 5 gal batch of beer using a 7 gal conical fermenter will there be too much head space in the fermenter? When I drop the trub out of the bottom to start secondary fermentation there will end up being more than 2 gal of head space above the beer.
Often wondered this myself.
There is enough CO2 generated during fermentation where this shouldn’t be a problem. Some folks will pressurize to 1-2 psi prior to dumping trub to avoid sucking oxygen into the fermentor. Don’t go higher than that, or you’ll have a mess at your feet when you open the valve.
Why are you removing the trub and leaving the beer?
“Secondary.”
Unless you can purge the O2 you would need to transfer it to something smaller. If your going to add fruit it may start fermentation and purge itself. May be better off to skip the secondary
I use a 12 gallon conical for 10 gallons. Never had any known problem doing that. Although the “secondary” is rarely ever needed. I still think true oxidation on a homebrew level is hard to do. If you drop the trub before fermentation has completely stopped, a new layer of CO2 will form anyway.
Careful not to open the valve before removing the air lock. It will suck the water or whatever is in it right in. Ask me how I know 
Another reason of dumping would be to harvest yeast.
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@hd4mark I too have found that out the hard way. Even sometimes today I still forget to remove my blowoff tube from the water…
Thanks. Me got the connical speidel on the island. Gonna pick up monday. And use them sunday. Good thing about the airlock.
Ive just done my first trub dump with my conical. I opened the valve about a 1/4" and led it slowly fill the jar. Instead of one big blurp it bubbled a few times. I will know in a week how it goes
