Here are some pics of my setup. The non-contact level sensor is loosely zip-tied to the container. Its red LED indicates there is liquid at that level. The airline tubing is connecting to the top, back right corner to a tube that extends to the bottom of the container. I have the refrigerator set at about 40 deg F (4 deg C). It's a little higher int he photo since i just opened the door. You can see the stir plate power cable, the level sensor wiring and the airline tubing coming in through the hole I drilled in the side.
You can see some mysis coming out of the airline tubing (the puffer looks like's he's about to eat it but is actually far away and is much larger than that).