Just leave it even though when it stops bubbling? The recipe called for a week in primary and a week in secondary. I'm aware I underpitched now. I just did what the recihe called for.
You're doing a RIS, that's a HUUGE beer, it is really surprising that someone would say that would reach final graivity in a week....but that's the problem with forgetting the yeast is in charge, and not us.
In Mr Wizard's colum in BYO this month he made an interesting analogy about brewing and baking....He said that egg timers are all well and good in the baking process but they only provide a "rule of thumb" as to when something is ready...recipes, oven types, heck even atmospheric conditions, STILL have more bearing on when a cake is ready than the time it says it will be done in the cook book. You STILL have to stick a toothpick in the center and pull it out to see if truly the cake is ready.....otherwise you may end up with a raw cake....Even if the instructions say it should be done, it might not be.
Not too different from our beers....We can have a rough idea when our beer is ready (or use something silly like the 1-2-3 rule (which doesn't factor in things like yeast lag time or even ambient temp during fermentation) and do things to our beer willy nilly....but unless we actually stick "our toothpick" (the hydrometer) in and let it tell us when the yeasties are finished...we too can "f" our beer up.
Many of us don't secondary unless we are dry hopping, adding fruit or oak, and many do THAT in primary as well...We just leave our beers in primary for 3-4 weeks which gives the yeast plenty of time to ferment are beer, but also to finsih the job (fermenting's not the only thing) and clean up the messes they made. )They are actually pretty fastidious critters and if we actually let them stay with the beer for awhile will do us good.
Or Lagering or bulk aging a really big beer like this...otherwise we skip it.
Even Palmer in How to Brew advocates this.
Leaving an ale beer in the primary fermentor for a total of 2-3 weeks (instead of just the one week most kits recommend), will provide time for the conditioning reactions and improve the beer. This extra time will also let more sediment settle out before bottling, resulting in a clearer beer and easier pouring. And, three weeks in the primary fermentor is usually not enough time for off-flavors to occur.
Even IF you choose to rack to secondary, wait til you reach your final gravity or pretty close to it, and wait a few days more..If I DO secondary which is rare these days, I usually do it around the 14th day...That usually gives plenty of time to reach my gravity approximately, and a few day of the yeastie to do their cleaning thing.
But you are making a huge beeer...that's why it's called IMPERIAL...I wouldn't rush any part of this process if you want it to be awesome...If I did secondary after 2-3 weeks in primary I would secondary if for at least a month, if not more to bulk age it, then bottle, expecting it will need a couple months more to carb and condition.
