"Gold" brew kit 2 stage fermentation ?

Okay, I went to the local home brew supply and bought the "Gold" kit...

it has a 6.5 gal bottling bucket with a spigot and a grommet on the lid for an airlock. It also came with a 6 gallon carboy. I've ordered a wine thief so that I can sample the carboy, since i couldn't figure out an easy way (clean) to sample.

I've been doing my primary fermentation in the bucket and then racking to the carboy for the secondary.

My question is will that extra space in the carboy cause oxidation?
Should I get a 5 gal carboy for the secondary, and use the 6 gal for primary and then only use the bucket for bottling?

___________________________________

HefeWeizen in the primary
Belgian Triple in the bottle
Brown Ale on deck

That much headspace isn't going to cause a problem. It's the spigot you need to watch out for. Many people have learned the hard way that those bottling buckets are designed for bottling, not for long term storage. If that's the way you want to go, then good luck with it. Just be sure to keep some towels on hand, or have it near a drain.

Personally, I wouldn't risk it. I'd use the 6 gallon carboy for my primary (I'm assuming you have a blowoff tube) and either buy a 5 gallon or just forget about secondary.

For what it's worth, I think you're on the right track. I'd use the 6 or 6.5 gallon vessels for your primary(ies) and pick up a 5 gallon for a secondary. If you're going to make anything that requires going to a secondary, that is. I'm not sure I'd want all the extra head space in using a 6+ gallon vessel for a secondary.

I have a bucket I've dedicated to bottling, but there's no reason I couldn't use it for a primary if I wanted to. You could too, but then you have to figure out what you're going to use for a bottling bucket if your buckets and carboys are all in use.