The safety fence does indeed float.

I made a 10-ft long x 2-ft tall prototype seine to test the flotation. On the bottom is 1/8" wire rope I had laying around around from another project. On the top is floating polypropylene rope with 1 foot sections of a pool noodle. This seems to float nicely and hang vertically in the water column.

Next, I will make a 50-ft long version for the algae collection.

[Linked Image from i.imgur.com]