Before I bought the Zoo Med controller, I called the manufacturer of the fridge (Uline) and he assured me that I should not exceed the maximum watts of the Zoo Med controller with my little 6 Cu/Ft jobbie. You are limited to a total of 1000 watts. The air pump does not pull much power at all. I would think the 1000 watt unit would be sufficient to run most refrigerators. Below is the reply the fella I spoke with said about refrigerators and I liked how he did a CYA. I did not have access to the inductive amp meter and assumed I was fine with this little fridge. I bet this could work with a larger one than mine. Let me know if you learn more
Thanks
Jon
Uline's Reply: "Like all refrigerators, there's a very short (just a second or two) of higher current then it falls off to normal operation. You should know that I can't recommend or approve any modification to our products like this, our units are Underwriter's Laboratory Approved and we can't approve anything other than the "as shipped" construction due to liability reasons. If you have access to an inductive amp meter, you could measure the full current draw on your system to verify the levels of current your designs will utilize."