OK! Here is a link to that pump at Amazon.Com:
Little Giant 1/12-HP 850-GPH Submersible Pump. 
It appears to be a good pump -- just not what I expected. And, not one I would want to use in a pond.
I have several concerns with using it.
The first and foremost is safety. It comes standard with a 6-foot cord that plugs into a regular 120 VAC outlet. It will definitely have to be on a GFI protected circuit. Everything I see about it screams DANGER if used in a large pond or small lake. Unless you have extensive electrical experience with outdoor and underwater electrical devices, I would not replace the cord, nor the plug on the cable, especially with a a splice. I'd be extremely reluctant to use it with an extension cord.
The plug at the end of the pump cord must be kept well above water, and it absolutely has to be plugged into a safe (inspected/tested) GFI outlet near the pond edge.
My second concern is that it does not appear that the pump has a replaceable or cleanable filter for small particles. It is the kind of pump that cannot handle much grit or other nasties. I suspect that is why you want to float it. It would have to be suspended off the bottom, in an area with minimal suspended organic materials (like algae) and inorganic (like clay or sand).
This pump is only rated with a 1-foot head -- meaning it will only push water at full capacity to one foot above the intake.
Maybe somebody else will see something different that what I've seen regarding this pump.
There are a lot of really good small and safe pumps available. Many are very inexpensive. For pond use, many operate on 12 or 24 volts through a very safe step-down transformer or power supply.
This is just my opinion, but I would not use this pump in a pond, except maybe for a very small pond with just a few hundred, or maybe even a few thousand gallons of water, and I wouldn't put the pump at a depth of more than about 36 inches.
Regards,
Ken
