I ran one all summer & well into fall on an outdoor 150 gallon tub. It held temperature with a 1,000w heater with no problem.
They are water resistant, not waterproof. I had it mounted on a pedestal, with a ziplock container around it. The keys would function through the lid without opening.
It's spending the winter in the garage, along with the empty tub. I don't foresee any problems with it come spring.