Question: what is the difference between duckweed and algae?
Answer: Updated at 23 Jun, 2017 10:39 PM. Watermeal and duckweed are commonly confused for algae. In the picture below, there is actually NO algae. ... Algae is easy to distinguish from aquatic weeds because it is either stringy and mat-like (see below) or is microscopic and gives the water a green tint.