When we clean our pond, in the spring, we drain it down by opening
a valve which sends the water underneath a very happy pine
tree instead of down our water fall.
We net the fish out and store them in a 150 gallon stock tank (many
time pond keepers clubs will have large tanks for loan for this
purpose). This tank is filled with pond water and a net is secured over
the top. It is mostly in the shade. We run an air pump attached to a
bubbler stone in the tank.
Plants are taken out. Placed in the shade, divided or repotted if
needed. We have no rocks in the pond.

The muck is scopped out. Dumped around trees for food. We do not scrub
the sides. No chemicals are used in cleaning.

Put the plants back in. We fill the pond from the hose, adding water
slowly over the day. Add the right amount of dechlor (available at
petstores - also important to know if your water system adds
chloramines which require a different product).

When the pond temperature is the same as the tank temperature (within
10 degrees) we put the fish back in.

A veggie filter is a setup where you run your pond water through a
plethora of plants. In our setup we run the water through a tank filled
with water hyacinth (which I don't think are available in your area)
and then into a waterfall filled with watercress. The plants filter the
fishy waste and use up a lot of the nutrients that single cell algae
thrives on and keep the pond clear. The roots of the plants catch a lot
of the mulm and dirt.

kathy :-)