I think the reason the thread has gotten very little attention is that the pond kinda looks flea-marketish, the only signs of actual life is the urchin.
I'm working on a design for an ourdoor greenhouse with a 1000g lagoon, it's actually going to be 2 lagoons, one will be sunk into the ground and the other elevated, the sunken lagoon will be to cool the top tank, much like a heat exchanger. If you search -- you will find several members who have such a setup with great results.