Yes, it can be kept outside, but I would shelter it somehow. I would not allow snow to pile up on it, for instance. No, stones do not need to be moved, although in the winter time you definitely want to make sure you have bubbles breaking the surface of the pond. Also, this pump may not handle a 4' depth so I would recommend putting the stones in a more shallow area of the pond, no more than 2 feet deep, to ensure enough oxygen is breaking the surface.
I typically use two sources in the winter time, something like this pump and a deicer as well, to make sure I have enough area open, and that if one has a problem, the other will still keep the pond open.
Date published: 2016-06-24