John, what about retrofitting your plant baskets? Cut them down to water
level or slightly below. Thread / weave fishing line or other sturdy
line across and through basket sides to create planting areas, (divide
basket into any number of pockets or chambers with line at bottom,
middle and top, etc.) put tall plants in center and have water celery or
watercress around edges to camouflage the baskets, add handles made out
of zip ties (as many as needed to support baskets while moving them),
voila!! You wouldn't need soil or rocks to support the plants as the
lines and other plants will hold them upright, so the baskets will be
lighter and easier to move, and there will be more room for roots to
grow and remove nutrients from the water.
--
Kathy B, zookeeper (OR)
3500g pond w/ 13 pond pigs,
2 sun worshipping pharaoh hounds,
and one "koi detective" lhasa apso
("don't bother me now, I gotta
keep an eye on those koi")

John Rutz wrote:

as I am planning to abandon the bio-mechanical filters this summer and
see what a giant veggie filter will do for my pond ...
... background ...
roughly 8000 gal KOI pond 20x20 bog, two 2400 gal
mag drive pumps and trickle tower.

plants will be Iris, water celery, cattail, some rushes,(aprox 150
plants total)
[should I put plants in] a couple inches of
base ball + sized river rock or a couple inces of clay soil?
the large plant baskets I use do stick out of the water about an inch
...