Originally Posted by yeastieboys9
I left the fermenter for a day more and the reaction has started. Now looking at a cm of foam in top. The temperature has risen to 15 degrees now, does this mean the total fermenting time will be greater? I was planning on leaving it. 3 weeks maximum.
15C (59F?) is on the cold side, but fermentation is exothermic, so it will warm up some, and depending on the ambient air temp, could get too warm, just keep and eye on it. And yes, colder fermentations generally take longer.
You can't really "plan" on when it will be done fermenting, you just have to let it do its thing. Wait for a few days after you see any signs of activity and take a gravity reading. Taste the sample. Wait a few more days and take another reading, and taste. When you have two or three gravity readings that stay the same, and the beer tastes fine, then bottle, or cold crash, or keg - whatever you plan to do next. And above all, have fun, you're two batches in to an AMAZING hobby!