Cooler with ice water (left) and cooling jacket with fermenter inside (right). Temperature controller and temperature monitors visible. As I suspect most home brewers do, I've constantly worked to improve my knowledge, equipment, and processes. I've gone from extract to all-grain, from my kitchen stove to a dedicated RIMS system, from plastic bucket fermenters to stainless steel fermenters, from pre-crushed grain to freshly-crushed. I've even made efforts to alter my water chemistry to better match the style I'm brewing. I think my beer's gotten better as a result of all that. One aspect I've not controlled well so far is fermentation temperature. In part, this has been because I didn't think I needed to. I brew primarily Belgian beer styles, and most of the Belgian abbey brewers let the yeast ferment at whatever temperature it wants to. They don't try to cool it, because they claim this can make the yeast stall out. They don't heat it