Thanks everyone.

Maybe this is a stupid question, but why not run the veggie filter
backwards and pull into the filter from the bottom?
My pond looks like this in cross section:

|~~~~~~~~~~| water level
| | | divider wall level
| | |
|__|_______|

The VF is on the right separated by a wall. VF is 10% of pond volume.
At the top, water can flow in or out across the divider wall which is
2-3" below the surface. The VF and pond are at the same water level.

The advantage is that no solids would get into the pump, but of course
anything that made it through the VF (or settled out of it) would get
circulated.



Derek Broughton wrote:
Mark Bannister wrote:


I have read SO much conflicting advice I thought I would ask for some
more. Our new pond is coming along slowly but it is time now to do all
the plumbing. Approx 700 gallons, 3' deep, concrete block. A veggie
filter runs along one side. Two water intakes pull water from a skimmer
and from the bottom of the pond. Water returns under the veggie filter
and midway down in the pond.
The questions a
What kind of filtration, if any, do I need before the pump?


Depends on your pump. I used to use a pump that could handle 3/4" solids.
As long as I wasn't worried about fish getting sucked in (never happened to
my knowledge), I didn't need a pre-filter at all. The problem with
prefilters is that they need more regular maintenance than the veggie
filter (they clog faster). If you can't get around to pulling the
prefilter to clean it, try not to need one. That means either a pump that
can pass solids like mine, or using the veggie filter itself as the
prefilter (ie, you feed water into the filter via gravity, and pump back up
to the pond after it passes through the veggie filter).


Do I need any filtration after the pump but before the veggie filter? I
assume the veggie filter won't do much in winter.


I'd say, no. The filter won't do much in winter - but you don't need a
whole lot of filtration when the fish aren't eating/excreting anyway. If
it's warm enough for the fish to eat, it's at least warm enough to keep
watercress growing in there. Even in milder climates where you have no
freezing and might have leaves or other debris blowing in all winter, your
skimmer will take care of a lot of that.


Aeration; there won't be any fountains or falls so I assume I need to
add some air.


Only if your fish load is high enough. Adding air is a requirement for
ponds where the fish use up all the O2 without it.


Air pump? Venturi "suction" type?


Either. Again, it depends on your fish load.