Hello! My wife and I are considering doing a backyard pond, but being
the type of person who's not going to jump into this totally blind, I
have been doing research to help figure out what this entails.

To summarize, we're thinking of combining together a garden railroad
and pond area. Nothing like combining two addictive and potentially
expensive hobbies, huh? :-)

We're looking at a pond of approximately 4x8 in size (freehand edge of
relatively oval shape), and a depth of 2-3 feet max. This will be
incorporated into a garden railroad of approximately 10x20 feet in size.
Hopefully the pond and railroad will compliment each other nicely.
We like the sound of cascading water, so are thinking about
incorporating a trickling stream feature which will fall about 2-3
feet over the width of the railroad (start the stream at one end,
and have the pond at the other end).

No waterfall is planned, as we like the sounds of babbling brooks much
more than cascading torrents. In addition, we might have a small
fountain feature in the pond to add interest and to keep water moving.
Definately some water plants will be incorporated into the pond area,
and we are most likely going to incorporate some small fish (goldfish
type swimmers, no plans for Koi or other larger fish that wouldn't
work well with a smaller pond like we're thinking).

For reference, we're in Iowa; and the location gets sun from morning
until late afternoon and there is a basswood (linden) tree nearby that
will no doubt contribute its leaves and flowers to the pond as they
fall according to the seasons.

Now, to the questions. :-)

- By my calculations, we're looking at somewhere in the neighborhood of
500 gallons. Does this sound accurate? When calculating volume of
a pond, does one figure in the amount of water in a stream feature, or
just the "pond" itself?

- For what we're thinking, is some sort of filter required, or will we
do OK without one? If algae becomes a problem, a UV filter would
obviously be required, but we aren't sure about the need for normal
day-to-day mechanical filtering.

- My thought for the pond/stream would be to sit the pump in the pond
as far away from the stream as possible, and then pump the water up to
the top and let it cascade down the stream. Should this give sufficient
flow through the pond to avoid stagnant spots (assuming that I orient
the stream output and pump on opposite ends of the long dimension of the
pond area).

- How does one figure out ahead of time how much pump to buy for a
stream? For pump longevity I'm not thrilled about buying a pump of
significantly higher capacity than needed and then valving it down to
the appropriate volume (too hard on the pump) My first thought would
be to build the stream, figure out what the flow from my garden hose is,
and then experiment with different hose flow rates until I get something
I like and then buy the right sized pump based on that flow rate and
head height? Is there a better method than this?

- Would it be better to buy one pump to run both the stream and water
feature, or is it better to have one pump for the stream and another
for the fountain feature? Or, should I figure out the turnover rate
needed (500 gal / 2 hours) and buy a pump for that rate (taking into
account the head height of the stream), and then valve and divert that
flow as needed for the stream, fountain, and any other water uses
desired?

- Like many who have ponds, we're concerned about mosquitos, and aren't
sure whether just having a stream and spraying fountain will prevent
eggs being layed/hatched (due to moving water), or if more serious
methods of mosquito control are required? I'm not thrilled about
running the pump 24x7, and would prefer to run it only during daytime
hours. However, this would give a good 10-12 hours of nighttime still
water that would be heaven for the skeeters.

- Would we need to bring the goldfish in each winter, or would they
survive under the ice? We can get pretty cold here in Iowa (down to
-20F a couple times a year at least with spells of several days at a
time of below 0 temps), and I'd be concerned that they'd either get
too cold and freeze, or the pond would freeze solid to the bottom,
since I'm looking at an average max depth of about 30". Also, due
to the lay of the land, part of the pond will be in a raised-bed
situation, so won't be insulated by the dirt below-grade.

- Would I be really wise to include a bottom drain in the plan, or for
something this small is that not really required? (FWIW, I'm planning
on using EPDM for the pond lining, without gravel or other bottom
material on top of the rubber).

- Are there other issues beyond what I listed above that my wife and I
need to be concerned about as we plan this pond (other than the
addictive nature and potential expenses)?

Sorry about the length of this post, but thanks for any potential
feedback!

Scott