It looks like a surprising variety or phytoplankton and single-celled algae! Maybe even some diatomic algae. I've been culturing green water to feed my microfauna (mostly moina), and wanted to check it out under my new digital microscope eyepiece. I think the combined magnification is somewhere between 1000x and 2000x. It's hard to say exactly because of the nature of digital eyepieces.

Using a Journey to the Microcosmos microscope, with a 60x Plan A objective, and a Celestron 5MP digital eyepiece.