Yes and red also.

See this thread for various plankton pics and the water color that goes with them. Brown is sometimes a late/advanced bloom where zooplankton tend to predominate.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Main=20172&Number=259527#Post259527

Last edited by ewest; 05/15/13 08:41 AM.