Before any one tells you that the mini fridge chiller will not work I will tell you how to make it work. This way of chilling the water is not the same as how most people make a mini fridge chiller. First you need to buy an aqua lifter water pump, it move about 3 1/2 gallons per hour. you need to drill 2 holes in the fridge for a tub the size of an air line, the water pump uses the same kind of tubing as an air pump does. You should also get some prescreen filters for the water pump, it is very easy for the pump to get cloged. You can buy both the pump and the prescreens from Marine Depot, I would suggest that you get at least 3 screens so that is one gets cloged you will have some on hand. Have the hose that the water enters in from in your sump, run the hose to the aqua lifter, then have a hose run from the pump into the chiller. On the inside of the chiller you will two bowls of water, one bowl needs to be in the freezer section of the fridge the other needs to be a larger bowl and needs to be in the main part of the chiller. Fill the Bowls with saltwater, it has a lower freezing temp. than freshwater does. The hose needs to first enter the larger bowl and needs to have about 25 feet of hose in the bowl, then the hose needs to go into the smaller bowl in the freezer, this hose needs to be about 15 feet in the bowl then the hose needs to go out of the other hole in the fridge and go back into the sump. The water will be very cold when it comes out of the hose, it will be mixed with the rest of the water and will lower the temp of the tank. I is very important that you have the aqua lifter on the same timer with the halides so that the water in the bowls get cold again while the halides are not on. The other way that you can have the aqua lifter controlled is to have it on a temp controler that will only have the pump come on at a preset temp. You will have to observe how stable the water temp is and adjust the amount of hose in the chiller by either adding more hose or removing some to make it chill to the temp that you want. This type of chiller works differently than other chillers because it it not trying to chill the whole volume of water to a certain temp. by making all the tank water go through the chiller, this chiller just supper chills a small amount of the water and the supper cold water gets remixed with the warmer tank water to cool the tank down. It is important that you use an aqua lifter to pump the water because it moves it so slowly. I have a 55 gallon with halides that also has a refugium. My chiller is a little different because I use frozen water bottles in an ice chest full of saltwater because I have not yet gotten a mini fridge yet I am going to get one soon but my chiller works the same way as the chiller above. I do have 4 fans in my canopy but my temp would rise about 6 degrees in one day. It would rise from 79 to 85 in 7 hours of having halides on. Now the temp. will only rise about 1 or 2 degrees in 7 hours of having the halides on.
I hope that it works for you also.