John,

The previous posters are correct about the problems of running a pool
filter for a pond. they do clog very fast.

Phyllis and I have a system with about 4,000 gal. We wanted a minimum
maintenance system.

The bottom drain is the submerged pump set in 5 gal bucket with as
many 1/2" holes as I could make in the bucket. The bucket sits one
brick off the bottom of a pit at the low point of the pond. The koi
swimming stir the muck, which then drifts with gravity and the water
flow to the pit. The big stuff (pine cones and needles and some
leaves) stays in the pit and is netted out once a year. We NEVER have
to clean the bottom of the main pond.

Our filter system is extremely simple and low maintenacne. We have
two series of smaller ( 8' long and 4' wide and 18" deep) ponds on a
berm that serve as veggie filters.. We have more than we need, but
that makes life easier. The berm ponds are full of water celery and
water hyacinth (with some parrots feather as well). The plant roots
serve as mechanical filters and as surfaces for bacteria. The growth
of the plants pulls waste nutrients from the pond. The water moves
slow enough through the veggie filters (about 45 min) that all the
muck settles out. The berm ponds have 2"bottom drains. Cleaning them
is simply opening the drain valves to let them drain onto the lawn.
They have 2+" of muck in them by the end of the year.

The water returns to the main pond over water falls and streams.

We run a UV filter only at the start of the year when the green water
algae start before the plants begin their growth.

The result has been very clear main pond water and a minimum of
maintenance work for the pond. The veggie filters are simply enough
to handle the entire thing. No settlement tank needed. No filter
pads to clean. Total maintenance is netting larger stuff from the pit
once a year and draining the berm ponds once a year. For our
purposes, this absolutely beats the tar out of more complex filtration
systems.

Here is a link to our pond site that has pics of the pond, for what
they may be worth.

home.bellsouth.net/personalpages/pwp-jameshurley

Jim