Speed of fermentation

My recipes generally call for a primary of 14 days but I almost always find myself needing to leave it a few days longer to get closer to the FG. In addition, quite often I don't get right down to the FG - which pisses me off. It's the only bit of my brewing that I'm not happy with.

Now you would normally say - "be patient and let it run it's course", but I am leaving it until it stops and still it doesn't get there. What also annoys me is that commercial breweries ferment in a few days and even people on here seem to get right down to almost their FG in about a week. Why do mine take so long?

Now I control fermentation temps as I have a temp controlled fridge. My initial thoughts are that I am extracting a lot of unfermentable sugars in the mash meaning that I get a high SG but will never get to my FG. My second thought is that the temp setting on my fridge controller isn't right. Lastly, I think that I'm under-pitching yeast. I normally use a packet of US05 or whatever. Maybe that's not enough?? But it seems enough for everyone else?!

Any thoughts?

K

I think your issue might be a combination of the things which you already suspect. First let's look at yeast health. I recommend doing an adequate starter and keeping it on a stir plate. Along with yeast health is oxygen. If yeast does not have oxygen to consume it will quit working and go dormant as soon as it burns the available O2. This is why I advocate using a pure O2 source prior to pitching.

Hot and cold break can play a part in attenuation as well. While some of the proteins are beneficial to yeast health, most of those compounds you want to try to get out of the wort prior to pitching.

Temp control is huge. I ferment my ales at a temp that is considered pretty cold (59*) but I also run fermentation for 14 days before checking FG. Once FG has been reached I raise 1 degree per day to 62* for my diacytal rest.

Lastly the instructions on kits and yeast packets are horribly inaccurate as far as time frame. The manufactures of these products want you to go buy more ingredients as quickly as possible. By trusting your judgement, experience, and most importantly your hydrometer you will know when fermentation has completed. I have some beers that finish in 7-10 days and others that require 14-21 days to drop out. I even have a few that undergo a second yeast pitch to drop the gravity. Don't rush the process, and take notes. One yeast strain will behave very differently from another and only through attention to note taking and experience can you determine what that yeast is up to. Even with that said brewers forget that yeast is a living body; it will often times develop its own personality and time line.

If it helps I have part of your problem too. I do usually get down to FG but my ferments usually take a couple of weeks like yours. Just like you I read about fermentations being done in a week on here and wonder how it's done. I've found the same with sprinkling packet yeast direct into the wort or using a starter.

I use a fermenting fridge too and I guess keeping the temp down to about 18.5 C probably slows things down. I find that upping the temp a bit towards the end (maybe to about 20.0 or 20.5) helps get the FG down. That said I'm happy with my finished product and if it ain't broke.....