Nitella looks like Chara, but is slick/slimy, rather than crunchy to the touch. It also has no odor. It's not real invasive. Grass carp will eat it, but prefer pondweeds over the algaes. With the amount of fertilizer, I'd expect a bloom, but with the rains you've had, a bloom may or may not happen. If you choose to control it, an algaecide works. Be careful, though. You can eradicate it, but with clear, warm water, you are likely to have something else take its place...and like that plant less.

Teach a man to grow fish...
He can teach to catch fish...