Buying Secondary - what shoud I get?

[zoebisch01]

So with better bottles do you get a 5 gallon or the 6.5?

They sell a 3 gal, a 5 gal. and a 6 gal.. The 6 would be for a primary with between 5 to 5.5 gal wort, or as a secondary for a 6 gal batch (although most people really don't make 6 gal batches except for me lol) and the 5 would be for use as a secondary or to ferment smaller batches I suppose. For primary fermentation you want the headspace and for secondary conditioning you want the least amount of headspace...so you size the secondary to the need.