bog filtration

[smaug]

Have any of you pondmasters or pond novices ever created a bog for the purposes of filtering the main pond?I have a heavily stocked 125 gal that I am considering doing this with.Any and all advice is welcome.

[Algenco]

untreated sewage effluent ran through 1 acre of cattails will come out clean, should work on a smaller scale too.

[smaug]

not as many replies to this one as I had hoped.Yeah,algenco thats the principle I am thinking of.I was considering a bog of about 8ft by 6ft with cattails and other marsh grass.