"Hal" wrote in message
...
On Wed, 16 Mar 2005 06:56:06 GMT, "George"
wrote:

and my koi appear to have grown substantially over the winter months, which I
find quite astounding. I guess they managed to find something to eat, since I
have only fed the fish during rare times when the water temperature was over
55
degrees (I know, this is likely why I now have the string algae, especially
since the filter was off for a month during the deep cold this January and is
likely not efficiently filtering the water as cold as the water is right now).

I'm glad your pond is in good shape and find it amazing that fish in
colder climates grow over winter too. Mine have grown a little, but
I've been feeding (small amount once a day) most of the winter, except
those few days the water temperature was below 40*F. I should have
lots of algae darkening my waters, but I guess the parrot feather and
a weekly (more or less) vacuuming of the bottom of the filter barrels
paid off.

I understand the bio-filter isn't much help in the winter, but I've
been tinkering with mine every year and my last change was to add
baffles in the first barrel to circle the water like a vortex with a
top exit, to cause settling of the heavier particles in the water.
It gets a lot of junk, but some sediment makes it into the next two
barrels as well. Every year of ponding seems different and without
controls to see what would happen otherwise, I can't really say this
works a lot better, but I like it.

Regards,

Hal

My filter is completely different. I have a prefilter to handle the grunge, and
I clean it about every two weeks (at least during the growing season). During
the winter, I hardly touch it (it would be a pain to do so anyway since I have
the pond netted in the winter). The pre-filter sits on the bottom of the pond.
My main filter is a suction-type filter. It sits on a ledge inside the pond
that I created especially for the filter when I dug the pond. The main filter
is submerged. My waterfall is constructed overtop of it in such a way that I
only have to move a few rocks and then unbolt the top to get to the inside of
it. It is a former jacuzzi pool filter that I adapted specifically for this
pond. A polypropylene hose attached to the pre-filter connects to a basket
strainer in the bottom of the main filter. I have about 75 pounds of coarse
porous gravel surrounding the basket strainer. The water flows through the
pre-filter, which removes the larger particles, then flows into the main filter,
through the basket strainer and the gravel. The pump is located about 8 inches
above the gravel (12" below the water surface). The pump is suspended from the
bolted cover of the filter by the piping. The cover makes the filter airtight
to prevent cavitation. I know it is time to clean the pre-filter when the water
pressure drops slightly. This happens about once every two weeks to once a
month during the summer. In the winter I rarely have a problem with water
pressure. I never have to clean the filter. It has worked great for me.

Biofilters aren't much help during winter. That is true. But what is important
in my opinion is to keep the filter bed oxygenated so it doesn't go septic. And
it helps to keep the water clear and oxygenated. I only use the aerator when it
gets too cold to run the pump. I have a de-icer for the pond, and it has worked
well this winter, so I only worry about ice buildup around the pump outlet and
around the waterfall, which is the only reason I turn it off at all.