I at first was hoping to not have to get a chiller with this tank, but it has become necessary. During the winter here the tank has been fluctuating between 80 in the morning to 84 when the lights go out. This is to much of a temperature swing, I am afraid of stressing the inhabitanta to much. I am also afraid when the house gets warmer in the summer the tanks temperature would rise even more. When I designed the refugium I had a feeling I would need a chiller, so I ran an outlet and return into the crawlspace just in case.

Being the miserly person I am, and the fact that a chiller would be around $600 I went the DIY route. I found several places on the web about people making chillers out of dorm fridges, but I did not think that a dorm fridge would remove enough heat from this tank. I did find other options out there, an old airconditioner and another using a dehumidifier. These seemed like a better solution for me. I could not find any of these items for what I wanted to pay for one(I do not like to buy something new if I am going to modify it beyond all recognition) so I found the next best thing, an old in wall water cooler. This had a 1/5 HP compressor so it should be powerfull enough to cool the tank.

I used 4 ball valves when installing the chiller. Two on the feed line and two on the return. I have one pair upstairs next to the tank and another pair down in the crawlspace. This was done so I could control the water flow from either place if I had to do maintanence on the chiller. I am using a Pondmaster 500 controlled by the Aquacontroller II to supply the tank with the cold water when needed. I knew this pump was rated to a head of 10.5 feet. I am pushing 8 feet of vertical, this is close to its maximum, but it seems to be doing the job.

I have installed a remote thermometer in the chiller to monitor the efficiency of the chiller. The chiller is set to 50 degrees F, I do not seem to be able to change this at this time. This seems to be the perfect drinking temperature according the manufacturer of this water cooler. I am using the seasonal temperature variation feature of the Aquacontroller II right now. With the chiller in operation I am able to keep the temperature within a half a degree. Without the chiller the temperature swing was around 4 degrees. It would be 80 in the morning and by the time the lights went out it was around 84 degrees. The chiller was able to drop the temperature in the tank from 85 to 75 within 6 hours. I did not anticipate it being able to do that, or I would not have done it. I did not realize the seasonal temperature setting in the Aquacontroller was 75. At the end of the 6 hours the temperature in the chiller had gone up to 56 degrees, so it was not powerfull enough for such a huge swing. I do not think this chiller, in its current configuration, is capable of keeping the water cold enough for cold water specimens. So far it is doing a fine job of keeping the tank at a very stable temperature. So far the chiller water temperature stays between 49 and 52 degrees. This does not seem to tax the compressor to much. It will go on when the water is being pumped and then shuts down pretty rapidly afterwards.

I am very pleased so far with the outcome of the chiller. I was worried at first with all of those stories of dorm fridge chillers not working. This design using a 1/5 HP compressor seems to work fine. I do not think I would go any smaller though, at least for this size aquarium.