I want to get my fermentation temperatures down – or at least stable.
Currently, I just stick the fermenters in a spare bathtub filled partway with water, throw a shirt over it, and point a fan at it. Evaporation cools it down a bit, and the large body of water in the bathtub ought to serve as a pretty good buffer against temperature swings.
However, what I was thinking of doing is taking my MLT (a 10 gallon rubbermaid circular cooler), and filling it with ice-water. Then take one of those rope-handled tubs, also filled with water. Then use a temperature controller to flip on two $10 pond pumps, to push water back and forth between the containers.
This would allow me to keep the water that the fermenter sits in at the exact temperature that I want, without relying on a fan or traditional swamp cooler. It should also only cost about $30, excluding the cost of the temperature controller – I figure that I’ll eventually need the temperature controller anyway if I move to any kind of cooling (and I also want to play around with it and my kegerator). A pump would also be useful to pump ice-water through my immersion chiller to get the final few degrees down (tap water is about 75°).
Any fatal flaws in this? The bucket holding the carboy wouldn’t really be insulated, but I can throw an extra blanket around it to hold some of the temperature. I’d also have to worry about condensation, but I’m already putting everything in the tub.