filtration?

hey everyone. i have been constantly researching and working on my new
outdoor pond. its 13x13 round and about 16-18 inches deep. There is no
natural shade to my pond, so im adding lots of lilly pads and other plants
to help that.
ok, as of right now... the pond is a green/brown color and doesnt seem to
be clearing what so ever. Whats the best way to fiter a pond.
right now i have 2 pretty strong pumps pushing water up into a large
container lined with filter material with a large hole in the side to allow
the filtered water to exit the container into my river/waterfall.
is there a better way, without buying a system, to filer my water? or is
this just a matter of time?
thanx!!