my astraea get on my glass everyone once and a while, but they eat slowly compared to how fast my algae grows. Magfloat, and phosphate reactor when things get out of hand.
The good thing is i have a whole side of my tank covered in green hair algae, sounds bad, but since it is rich in micro life and the shrimp perch on it almost all day long in a viewable position, its a small price i have to pay.