JEC - "those curly root like pieces that float on the surface" are the flowers that will produce seeds. The seeds are fertile and a dispersal method. Did you plant the standard size eel grass or one of the shorter growing varieties (8"-16") such as V. nana, V.rubra, corkscrew, or twisted??

In the northern US eel grass produces those flowers once a year usually in late July - August. Keep us updated as the summer progresses about the duration of those flower buds in Florida.