Steve wrote:

Well I have been reading for a few weeks and finally decided to do a pond.
I will probably just put a few small goldfish in it nothing big. It will
be
a preformed one from HD 165 gallons and 18" deep. I will bring in the
goldfish in the winter to an aquarium ( i have 4 of them).

My questions is : I will be getting a pump and filter combo (Beckett
Small
Pond Filter Kit Model 7040210). Will I be able to run a waterfall that is
2
ft high and about 3 feet away from where the pump will be located?

You need to figure out (first) what the flow rate of that pump will be
at "head" of 2'. Rule #1 is that it is going to be less than the 350gph at
which the pump is rated. Sometimes it's _much_ less.

This page (http://www.pondtechnology.com/pages/pumps.html) offers the
following rule of thumb for waterfall flow rates:
- light flow = 50 GPH x waterfall width (in)
- average flow = 100 GPH x waterfall width (in)
- strong flow = 200 GPH x waterfall width (in)

So assuming you can get half the flow over the waterfall - either by
diverting some of the flow or going through the filter first, you can get
a "light" flow over about a 3 1/2" wide waterfall.

Personally, I'd consider a 350gph pump to be about half what you should be
using for filtering a 165g pond, and lifting the water another 2' will slow
it more, so you're really in need of a bigger pump.

I see no real advantage to using two pumps over a single pump. A single
pump going _through_ a filter and then over a fall has the benefit of
giving you an audible indication of the state of the filter - when the
falls slow down, you know the filter needs cleaning.
--
derek