On Wed, 10 Oct 2007 16:53:31 CST, RobJ wrote:

I have a backyard concrete pond that measures 10'W x 13'L x 3'D.
(2,400 gal)
Until recently it has been FULL of lilies and a very dense root
system,
anchored by substantial sediment. No fish. It has never been filtered
but never had an algae problem because of the amount of vegitation
surface coverage. This year, however we had an infestation of
caterpillar type worms that chewed all the leaves, leaving only stems
and a very ugly pond. I decided to drain and clean it and start over.
This time I'd like to have a few Koi and a more attractive pond. I am
planning on putting about four inches of gravel in the bottom, but not
sure
if this the right thing to do. What kind of filtration/pump equip
would
be best suited for this size of pond?

No to gravel on bottom. If you want to go with koi I highly suggest a retro
fit for a bottom drain to keep a filter out of the pond. Easier maintenance
and leaves more room for the fish to swim. You can see how we did this on
my website, *My Filter* below. ~ jan
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Zone 7a, SE Washington State
Ponds: www.jjspond.us