Hi Derek -
Your pond doesn't need that many diffuser locations. I would recomend one at A, C, and the other to be turned on in a shallow area to run during the winter months if you deside to winter aerate. During the winter if there is any open water, the pond is not safe for any activities. You could just have the two locations and if you are having a harsh winter with thick ice and snow you could turn the system on long enough to create an opening for diffusion to occur.
You also do not have to run the expensive weighted tubing the 300 feet to your pond. You could run 1" pvc to the side of the pond where you connect to an underground valve box that splits into the separate air lines. I will size and design a valve box system for your pond and send it to you.


Sue Cruz
Vertex Water Features
www.vertexwaterfeatures.com