Or what about a Venturi to suck air into the water. I would lose some pump efficiency. Lots of different things to consider I guess.
Just as another thread about your goals changing. You see one picture of what Cecil does and it makes you want to push your pond harder.
I'd stay away from pumping air into the water via a Venturi. If you are pumping ground water you already have supersaturation of nitrogen which you want to reduce the potential of gas bubble trauma. Why would you want to add more nitrogen?
Do I understand you correctly that you want to pump in water in the winter? Why when you don't have to?
Two rules I live by even in my recirc systems:
1.) Don't do something that is not necessary that will increase your utility costs.
2.) Use gravity flow whenever possible as in a gravity drop through media to aerate and blow off gases or to move water around.
