I am wanting to make a biological prefilter out of a large flat
rubbermade container using some coarse and medium density pads and
springflo for the bio medium.
The pre-filter will be placed at the bottom of my pond.

Pondmaster and little giant sell theirs for around $60 for a SMALL 12 x
12 or 12 x 24 size...but they look very easy to make.

Anyone have any links?

TIA