Checking on my pond this morning I was surprised to see this formation, it is hollow inside where the slow flowing water from the hose is trickling through.
The pond is almost completely frozen over, I leave my pond pump running all day, every day to make sure that pond doesn't freeze over completely, the hose also helps a little.
It is dangerous for the fish if you leave the pond completely frozen over because gases that build could suffocate the fish, the ice would stop oxygen getting through.
