They looked like pics from the now or neverglades email I got, definitely green algae. Hydrilla is unmistakeable and it only takes one lesson to leave it alone. It grows mostly where the sun can reach the bottom, I think, because it isn’t found in deeper water. Bad for us that most of our lakes are shallow. Used to bass fish the deep water edges with crankbaits, great fun to watch the fish dart out of the weeds and hit the crank.