ac7av
Bring on the FISH!
While I can't say for sure on a reef tank, I wanted to cool a 55 gallon tank from about 65F to 55F. I used a new dorm fridge, and ran a line through the freezer and the fridge with various lengths and materials including 6' titanium. The best I could get was -5 deg F.
So I have to agree that it is not a very efficient method.
Eventually I filled a 25 gallon cooler with RV anti-freeze, used the 6' piece of Titanium as the aquarium heat-exchanger, carefully placed the heat exchanger from a dehumidifier into the cooler and used a temp controller to turn the dehumidifier on and off. A maxi jet to push water through and it worked like a champ.
So if you are into the pile of junk in the corner look, or really want to DIY, it can be done.
FWIW I have a real chiller now
Thank you, a dehumidifier again has a much larger compressor and higher btu rating, much like an air-conditioner.