How do you sample to make sure you reach the right FG? Or do you just let the yeast run it's course as I have done and hope it all works out? I have a hunch that I should "turn off" the yeast at a very specific time instead of letting it sit on the yeast for a week. I just brewed a batch and pondering this, more of an open forum question rather than specifics.
Not sure how others are doing it, but I sample throughout fermentation in the most sanitary way possible. I watch my gravity and if my sugars and yeast pitching rates are spot on I let it finish to my target and then rack to a keg, chill and carbonate.
Make it correctly and forget it for 2-3 weeks...then take a gravity and you almost assuredly are at final (terminal) gravity for most beers. If bottling, and you are nervous, take another gravity 3 days after the first gravity...it should be the same.
A week (or more) of sitting on the yeast after attenuation is finished will allow the yeast to clean up some of their byproducts, making better beer. You don't want to "turn off" that process.
This is exactly how I do it. No need to open the fermenter without reason. I know the beer will get done. If I were to do a really high OG beer I would definitely make sure there were two identical readings at the end (and leave it ferment longer too).
I won't disagree with that and, indeed, I live by it (I ignore it for 2-3 weeks, as GreenKrusty suggested). However, after racking to secondary, to a keg, or to wherever, is there enough yeast left in suspension to do that job? There's certainly enough to carbonate it.
Pitch the proper amount of yeast, and let it go until it is done for all the reasons above. You can control how long the fermentation goes in the mash or boil. You have less control over this with extract, but you still can take some steps.
Based on temperature and OG, I will start testing the gravity after a week-10 days after the yeast is pitched. I mind my anticipated FG, and when I see it is in the ballpark and has stabilized, I am ready to either condition further, or bottle. When you say "how do you sample", I have a wine thief that allows me to dip and extract a small, but large enough amount to read the gravity. You can drop the sample back in if you use one, but I keep whatever I pull out to taste it, as well.
I just let it fly, let it ferment for six days. Went from 1.064 to 1.020. Racked it over to secondary and added 1oz. of Galaxy pellets for dry hopping. Good mouthfeel and smooth malts, can't wait for it to finish!
I always taste everything at every stage, from the wort during mashing to post boil to the gravity samples to the pre-conditioned beer... everything. Hopefully I develop a taste as to what things are supposed to taste like along the way.
