How do you get a stuck fermentation

Hey im looking to get into all-grain here in a little bit but im just wondering, i know i have read about it but forgot, how does stuck fermentation happen and why?

 

Poor yeast viabilty,underpitching with poor yeast viability,temperature shock. Pretty large abv beers-not enough yeast. Make a starter especially with high abv beers or generally when using liquid yeast and aerate well or pitch enough yeast and keep temps consistant. Ive never had one stuck, I dont brew super big beers either,the ones I did like 8% or 9% even probably underpitched still had no problem. Certain yeast wont tolerate higher abvs as well.

 

Any one of a hundred reasons. Just keep your mash and fermentation temps steady, pitch enough yeast, and aerate.... Oh and don't forget to pray to Ninkasi.

 

Going into all grain I would be more worried about a stuck sparge than a stuck fermentation.

 

A stuck sparge? I've heard of that been dont remember what it is, how does that happen and y?

 

http://beersmith.com/blog/2009/04/24/avoiding-a-stuck-sparge-for-all-grain-beer/
On stuck sparges.


FWIW, stuck fermentation can actually happen if there are not enough fermentable sugar. I pitched the right amount of yeast, controlled temps with tolerance and then found my recipe, although beersmith never alluded to unfermentable sugars, just simply didn't have enough sugar to get from the anticipated 1.062 to anticipated 1.011.

 

Stuck fermentations usually happen when you mash at the wrong temperature(like way off)

I know someone whose cheapo thermometer was off and he didnt realize it and mashed at like 168 for an hour...

His IIPA wouldnt drop below 1.040 because there was so much unfermentable sugar lol.