Congratulations on the setup.
This is something I have played with for years with aquariums as well as other things that need to be cooled.
When it comes to refrigerators, the negative response you will see the most is that the compressors are not built to handle the load. Refrigerators and Freezers are built to keep cold things cold or in other words, not have to run all the time.
However, that is only partly true.
The truth is that no compressors are really built to run 24/7 be it fridge, air conditioner or chiller. If your setup is powerful enough that it doesn’t have to work hard (as yours seems to be), then you should be alright. The problem is when people run out and buy things too small, like a mini-fridg, and expect it to keep up with the constant 5-15 degree drop they need.
I made this mistake when I added metal halides to a 90 gallon reef tank and figured a mini-fridge would be great. I drilled holes in the top and ran a coil of tubing inside the unit. A great bonus was I could keep fish food in the freezer section making my wife happy that the “icky stuff” was no longer in the kitchen fridge. It worked and it worked well…for a while.
A little over a year later, in the hottest days of summer, it gave out. I was broke at the time and had change out packets of dry ice floating in my sump for the rest of the summer. However, I still lost a few corals.
Before the next summer, I splurged on a n inline chiller. I had to put the icky stuff back in the kitchen fridge, but it still runs today (7 years later). I couldn’t tell the difference in noise.
A couple of questions.
That aluminum radiator actually sits in your tank water?
If so, I would freak out if it was in a reef tank, but is that relatively safe in a planted tank?