Pond Boss Forums INTRO Questions & Observations Geo Thermal

I am in the process of building a home, when the subject of heating and cooling came up I was told by my builder that my pond would be a perfect set-up for a geo thermal system. For those not familar with geo thermal, basicly its a trenching system with a polymer type tubing garenteed 50 to 75 years, buried 4 to 6 feet deep in the ground, snaking or coiled about 450 feet and connecting back to the house into a heat pump, an enviormentally friendly ( this next word makes me nervous ) "antifreeze" runs through the pipe and draws the heat from the earth in the winter, in the summer it takes the heat in the home and transfers it to the ground. I am told the advantage of the pond is the option to lay the coils on the bottom ( about 900 feet or so )like a slinky. In Iowa the requirments are to have at least a 8 foot depth and not less than a .5 ac pond. My pond is 2.75 ac and 14 feet. The advantage of sinking the coils in the pond is the savings on the trenching expense which is pretty costly.Has any one had this install done on their pond? Pros.... Cons? Belive it or not the heat is suppose to conduct through the pond better than the earth buried systems, even in the winter. at the very least it would be good fish structure. "RIGHT"? - Thanks