I have a question on aeration based on earlier posts. I get that moving water vertically allows oxigen to move into water from the atmosphere above the pond and then circulate based on the water moved by bubble, but what about oxigen in the bubbles themselves moving into the water? Is this really not a significant factor? How come this is different compared with an air stone in a fish tank? Is it that the size of the bubbles from pond aerators are much larger and have too little surface area?