Designing Pond Circulation

I have a 6500 gallon liner pond and I need some advice on creating the right circulation. The attached document has a picture of the pond with my proposed circulation plan. I'm looking for the experience of others to refine it before I complete the installation.

It's a gravity fed filtration with three return feeds planned:

1. Waterfall (one half of output from main 16,000 litre an hour pump)
2. Return 1 (as on diagram, second half of output from main 16,000 litre an hour pump)
3. Return 2 (return from skimmer pump, 4000 litre an hour I think)

The diagram shows where I plan to install a wide front skimmer and the returns.

All of the proposed design is open to change. The waterfall will be operating in the summer month. What I need to decide is where to site the skimmer and the other two returns.

The returns will be at surface level (or just below). It's an existing liner pond and I'm not planning on cutting into it for the returns. The pond is banked, with a ledge about 10 inches below surface and 12 inches wide. After that is banks down to a maximum of 5 foot depth in the centre/rear.

Many thanks,
Cliff