I've heard mentions of people using tertiary, quaternary, quinary, etc fermentations. Does this really provide any significant benefit beyond secondary?
I think this same answer applies here:
What's the point of secondary fermentation
The purpose of n-ary isn't more fermentation, but aging, clarifying, etc.
So for me, no it doesn't provide any additional benefit. The only time I use a secondary vessel is for fruit additions or extended aging. I've never found a need for a third vessel.
This. I've heard of some people who are overly anal about clarity racking three or four times, but it's honestly not necessary and just increases the risk of oxidation or, to a lesser extent, infection.– Jeff LNov 15, 2010 at 22:22
1Sometimes the purpose of n-ary fermentation is more fermentation. You can work with higher "effective" O.G. by adding additional sugars ( and possibly more yeast ). I make a quad that I add boiled molasses to after primary fermentation; and I add a type of indian date sugar boiled in water and additional yeast before tertiary fermentation. For extremely high gravity beers I don't think this is unreasonable.– SindhudweepNov 16, 2010 at 17:58
I've heard of having a tertiary phase if you add fruit (etc.) to the beer during the secondary, to help precipitate out the fruit particles before bottling.
I can't get a pumpkin ale clean with only a secondary for the life of me. Next batch I plan on using a tertiary. Just be careful with splashing, I've been careless and oxidized the hell out of an otherwise good beer before.