Wood,
I suspend mine about 3 feet below the surface in the trout pond. I suspend it with gallon orange juice containers or something similar. Glue the lids on with PVC cement and run a nylon rope through the handles onto the diffuser. Mine consists of a duel airstone setup with a checkvalve. I use a weighted airline. In really cold weather you may want to slightly bury your airline to the pond edge. Don't use clear plastic milk jugs as they will not last. I would run it continuously in winter for in severe temps you pond will form ice almost immediately when you turn it off.
You don't need much flow. I use a 1/20 the horsepower model from a company known as Stoney Creek in Grant Michigan that puts out .7 cfms and it's the one I use on the bottom of my small trout pond the rest of the year. Doesn't use much electricity. If you have anymore questions give me me a holler!
