4 months old tank, finished cycling 2 months ago. The NO3 and PO4 has been steadily falling and are now undetectable. Rocks are covered by white furry looking algae that doesn’t get long than 1 cm. Was surprised when I looked under the microscope, see below at 100x. The strands of the algae a remarkably segmented, with only a few chloroplasts in the center of each segment. Any idea?