Here are two fermenting worts. The one on the left has been dry hopped. That is what is floating on top. Temperature control is of the utmost importance during fermentation. This is a closet in my basement that happened to be about right. Be aware that the activity of fermentation will generate heat (2-5 degrees) and this must be compensated for.
This is one way of controlling temperature. Here the fermenter is in a bucket of water inside a chest freezer that is being regulated by a controller (Johnson Controls). You can see the temp probe on the left. It is silver and is taped down to the top of the freezer with a piece of black tape. The controller simply turns the power on and off depending on the setting. When the temp rises above the setting it turns on the freezer and once it drops the temp it turns the freezer off. The range is about 4 degrees.
