What have you tried to clear it with? Have you put any water in a clear jar to see if somethimg settles and the water clears? If it clears quickly (12-24 hours) you may have a fish you don't know about in there (Bullhead cats or carp). I love alum! The size pond you have, a 50lb bag would probably work mixed with .5 to 1 part hydrated lime. If you fetilize your yard the green is probably FA. Whats the other runoff from? Any walking catfish around you?

Try this link

http://agnewsarchive.tamu.edu/dailynews/stories/WFSC/Mar3106a.htm

Last edited by Rainman; 02/12/08 05:33 PM. Reason: to add link