try adding a layer or 2 of quilt batting to the final stage of your filter
before the water returns to the pond. it will catch an awful lot of greenies.
you may need to replace it once as it will get clogged quickly.

Karen
Zone 5
Ashland, OH
http://hometown.aol.com/kmam1/MyPond/MyPond.html
My Art Studio at
http://members.aol.com/kmmstudios/K....M.Studios.html
for email remove the extra extention