Sorry I haven't replied sooner (busy weekend).
The pond kept water most of last summer but we have unusual regular rainfall. When we do get rain it gets plenty of runoff so it fill quickly. Otherwise I would have to top it off with a hose at times. I suspect that might kill FHM...
Predators would certainly be a problem. Frogs, turtles, snakes, and coons, all visit regularly. Haven't seen a heron in it yet...
A winter ago I left a batter powered aerator in it for a couple of weeks to see if it would keep the ice off (it worked well). I could run one in the summer with no problems...
