I also live in Zone 6b (Haymarket VA). I leave the stretchy fabric hose out in laundry room for winter pond fill up. The outside hose bib sits under the outside dryer vent outlet, so not a problem re freezing and I time my fill ups when weather is above freezing during the day. I keep my waterfall on during winter. I have a heater which switches on at a certain temperature. I use a commercial Fall Pond maintenance product when weather turns colder.
However, I do not muck out the leaves that escape the leaf net. One early spring I scooped up the remaining leaves and woke up by hand sized bullfrog, so now I leave it in but then I'm usually late in the early spring and I end up with fish egg jelly in the muck if I wait to long. Should I be clearing out the bottom totally? some of the posts sounded like that would be better.