Fermenting time for an imperial IPA

1) Changing what?
2) Fermentation will be done when it's done. Yeast don't know about 1,2,3, or any other method. Use a hydrometer to find out if your fermentation is finished or not. Take a reading, and if it's about what you expected for final gravity, wait 2-3 days and take another. If it hasn't changed, fermentation is done, though you may still want to leave the beer in the fermenter a little longer to allow the yeast to clean up their byproducts.

 

H.Y.D.R.O.M.E.T.E.R

You do not tell the beer when its done, it will tell you. Check the gravity and the taste. No need to rush anything. Patience is a big thing when brewing and realizing that you control the environment for the beer to ferment but you can not control when it is actually done.

 

Great question.

OP, I usually dry hop (which I hope assume you are doing) in the primary. It will reduce the risk of any sort of oxidation that can/will be picked up during a transfer. Like VikeMan said, yeast is done when it's done, this is why I'm suggesting dry hopping in the primary...to make sure it is done. If you still use your 1-2-3 method, you will have the beer in primary for 3 weeks, I'm sure it will be completely fermented and full of dry-hoppy goodness by that time.

 

If you have a homebrew shop locally, go grab a beer/wine thief. Or you can grab a testing cylinder and syphon the liquid into it and measure the gravity from there...plus you can taste it.

 

I would avoid testing it directly in the fermenter for many reasons. A broken hydrometer will ruin your batch, as will an infection.

 

I can tell you I just went through this process with an Imperial IPA. First off the beer came out really nice. I went with 12 days in the primary and 12 days in the secondary ( dry hopped with 2 oz fresh crystal hops) Worked perfect. Final gravity was hit perfect as well, using the WLP001 yeast.