Okay, I read all your fine suggestions and did some thinking/looking/investigating. I finally came to the realization that I didn't want something so complicated as a float system. Here's what I did;
I have a geo thermal heating/cooling system
The system has a 4" pipe taking the discharge from open loop to the pond
I had my geo guy come over and look to see if he could tap into the main well line in the house and give me a valve to regulate 5gpm to the geo discharge 4" pipe
The geo guy tapped in, installed a ball valve, we found a spot on the valve which gave me 5gpm, then discharged the water right into the existing 4" pipe.
I can turn the water on and off as needed, adjust the flow, it's frost free, all is good.
Thank you all for the brainstorming.
