http://www.skippysstuff.com/biofiltr.htm

I built the above filter for my 3,000 gal pond in upstate NY. I clean it 3
to 4 times per year. I keep wild iris in the top of it and let it freeze
in the filter full of water for the winter (keep the water in it thru the
winter drain and clean in spring before turning on pump). I do use a
mixture of screen with some floor scrubber pads cut up that I bought from a
local company. I also have a uv light so the filter doesn't keep the water
clear on its own.

See my pond here http://community.webshots.com/user/peggy256

"Todd " wrote in message
...
Can anyone recommend a biofilter or good plans to make your own

Thanks
Todd