It could be a phytoplankton bloom and your chocolate may be a shade of reddish brown algae bloom that can form in late fall. Try the jar settling test to get a better idea if it is algae or sediment. If it is sediment something is happening on the pond bottom sediment layer.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=396493

Last edited by Bill Cody; 12/25/16 12:25 PM.

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