Thanks for the awesome tips. I found these on ebay, look like they might work well.

I can try the foam pipe insulation as another easy to buy and install 'float' material.

If you zip tie the foam pipe insulation then you probably still want to puncture through the foam and the middle of the rope to prevent spinning of the zip ties.

I think I can get by with 100' rope but i do wonder how people get the one end of the rope out to the middle of the pond, and then circle back to the shore to trap the debris without a boat?