A real cheap and easy way to cool your DWC water temp and keep it constant.
A water pump pumps warm water from your bucket into the fridge. In the freezer is a spiral tube to get as much surface area possible for good heat exchange. The cooler water then gets pumped it back into your bucket.
Hook the fridge and water pump to the same power and add a thermostat. When the water goes over the pre determined temp, the thermostat kicks in, turning on the pump and fridge and keeps the water on the right temp.