Originally Posted by jbone728
Perfect, thanks a lot! I thought it was too low, my FG that is, and I thought I did something wrong, since i didnt ferment it as cold as I probably should have...around room temp., 75-78 degrees fahrenheit. This has been the hardest part, I just want to taste it already! about 1-2 more weeks tho, I will let you guys know how it comes out!
Yes, that's too hot for fermentation. But the yeast will still work at that temperature. The reason you want to keep it cooler is for flavor. Anything above about 70 degrees (beer temperature, not ambient temperature) causes some off-flavors in the beer like fruity flavors or "hot" alcohol flavors. Some yeast strains do better than others with hot temperatures, so it is really yeast strain dependent.
What works really well is chilling the wort to 62-65 degrees before adding the yeast, and then keeping in a cool place (62-65 degrees or so) or sticking it in a water bath in a cooler with some ice blocks. An active fermentation produces heat, and I've seen the fermenting beer be 10 degrees warmer than the ambient temperature. Which means in a 72 degree room, the fermentation temperature can be 80+ degrees, so that's about 10 degrees too warm.