Fermenter size?

[Kosh]

I'm soon to begin brewing BIAB 3 gallon batches. I will probably get a catalyst 6.5 gallon fermenter with trub valve.
Is that too large for my 3 gallon batches? Seems nobody makes a nice 5 gallon 'total' conical with trub valve! And all 3 Gallon versions I see are only designed for 2 maybe 2.5 Gallon fermentation. The yeast will make A blanket of CO2 the cover of the wort however do you think the 6.5 gallon is too a bit overkill? Wanting To eliminate transferring to a secondary So purchasing with trub collection valve.
Thanks!

 

[Nosybear]

The size shouldn't be a problem.

 

[Mark Farrall]

You'll read stuff about too much headspace occasionally. I'm yet to see anything other than opinion and contradictory small scale experiments to back that up. But that might be my confirmation bias as I've been using the same sizing as you.

 

[BarbarianBrewer]

Head space only matters in secondary. And even then I expect it would be a problem if you are aging the beer. On the plus if you ever want to brew a 5 gallon batch, you'll already have the fermenter for it.

 

[Kosh]

Head space only matters in secondary. And even then I expect it would be a problem if you are aging the beer. On the plus if you ever want to brew a 5 gallon batch, you'll already have the fermenter for it.

Thank you everyone for the replies! That's a very good way to look at it, barbarian brewer!
There is a lot of great information on the internet, however there is also a lot of contradictory information that can worry you to death if you let it!
I stopped brewing about 25 years ago due to some bad experiences... AKA Mr. beer. The product was just bad in my opinion back in those days. I've heard it's very good now however still expensive.

Anyway during last year I have been studying day and night on beer brewing, Learning ingredients, and drawing up recipes on different software platforms. Did a nice extract chocolate porter a while back, turned out very well!
But I'll be getting into BIAB soon I hope, Got some expenses to get out of the way 1st then full steam ahead on my equipment! Cheers!