Size of conical to get

I decided to join the forum after being unable to find this - is there a problem with under-filling a conical? Say I want to get a 14.5 conical typically used for 10 gal batches but only fill it with a 5 gallon batch. I probably sound paranoid here but is there any issue you can think of with a batch too small for the size that would affect fermentation? The shape should not influence it, right? The biggest disadvantage I can think of is the additional oxygen space. Anything else?

I'd like to ideally go with a larger than needed conical since they are not much more expensive and will allow me to not need to re-invest as I go with larger batch sizes down the road.

is ok. O2 will be quickly used up before the yeast gets going.

I'm thinking about doing the same thing. Currently only doing 5 gallon batches but I am going to buy the 14.5 conical fermenter to future proof myself. From everything that I have read the amount of co2 that is produced will fill the extra space rather quickly. My last decision is tri-clamp or regular connections.

-Jason

I do both 10 and 15 gallon batch in my 22 gal conical. No problems

Heck, my 17 gallon (plastic) conical doesn't even seal completely on the top. No real issues there either...although I don't leave things on as long.

Good enough for me, thanks for the confirmation.
So 14.5 is looking like my best bet. Now for the rest of the features...

I done a 4.5 gallon batch in my 22 gallon and it came out great.

For future searchers with a similar question - I found this on Blichmann's website:

Can I Ferment Smaller Batches in My Conical? <back to top>

YES - you can ferment, say, a 5 gal batch in your 14.5 gal conical. The CO2 gas from fermentation will fill the head space and protect your beer from oxidation. The only drawback is that you'll have less head pressure available to push out your yeast. Dumping more frequently will resolve that issue. Or you can simply use the pressurization feature to push it out.

Ordered mine today, I went for the Tri-Clamp fittings. Oh boy, can't wait for my next brew.