Just an idea on the siphon. Or at least this is what I did last fall and it seemed to work well. 2 inch inlet on a trash pump, 2inch outlet also. I used 2 inch black irrigation pipe from menards. Wasn't too bad on the wallet since i only need 100 ft of outlet. I started the trash pump and once it was pushing water out the end over the dam I turned it off. The water siphoned right through the pump and everything. Once I hit a dry spot I just adjusted the inlet and restarted pump for a few minutes. It took about 2 weeks to empty it. It was a little under 1/2 acre probably and 6 ft deep. If you have larger pipe it would even be quicker, buy I liked the idea that I could just leave the pump in place. When I was planning this I always figured I would have to place the outlet pipe in water quickly before the siphon stopped but there was no need to even unhook the pipe from the pump. I had a homemade filter on the inlet that I made out of PVC. It was shaped like a "T". The entire process was much easier than I thought it would be. Now all that being said, I can not really use it for anything else like Rainman's idea. I have actually thought about putting a permanent siphon in to help remove bottom water. That might be a project before I call it finished.
If there is such a thing as finished. I have done a lot of pumping and messing with pumps due to this leaky pond and I have to agree that a 3/4 hose will take you forever, even if you have multiple hoses. When I was using the two inch, the water was coming out with incredible force. You can not get that with 3/4 inch.
