6
Polyethylene liners are lowest
in cost but don’t last very long
(perhaps up to 10 years); PVC
liners are mid-range in price
but are stronger and may be
reinforced with netting; and
Butyl sheeting is the most
expensive but also the
strongest, tolerating both
sunlight and frost. It can be
expected to last 20-50 years.
Beware of using swimming
pool liners or other materials
not designed for ponds,
because often they have been
treated with chemicals which
can be toxic to wildlife and
plants. Look for products
marked “fish safe."
When using a flexible liner,
pad the ground first with a
thick layer of newspaper and/
or sand to protect the plastic
from being punctured by small
stones.
To determine the size of liner
needed, measure the length
and width of the pond, adding
an additional foot to each for
overlap on the top edge, then
multiply the maximum depth
times two and add it to the
first figures.
Let the water settle before
trimming away any excess, but
leave enough material to fold
some over the sand or rocks
that are holding the edges in
place as you fill the pond. Hide
the remaining visible edge
material with additional rocks.
Leaving some excess will let
you make adjustments in the
future, if necessary. Using
stones and plants around the
edges, putting some smooth
gravel in the water, and using a
dark-colored liner will all serve
to make the pond look more
natural.
Pond Maintenance
Clean out debris regularly,
because it can rob the pond of
oxygen as it decomposes. Some
owners use netting to catch
falling leaves in autumn before
they enter the water.
Destructive insects should
be washed off the plants or
the affected leaves should be
removed. Don’t use any
pesticides.
In winter, discard tropical
plants and move hardy ones to
a depth of 18 in. or more. Stop
feeding any fish when the
temperature no longer goes
above 50 degrees. They have no
digestive systems and rely on
the bacteria that only grows in
warmer weather.
The fish will instinctively
move to the deepest part of
the pond. When temperatures
go below freezing, it is
necessary to let oxygen into
the water and also to let any
gasses caused by leaf
decomposition escape, or else
the fish will suffocate.
A heater or deicer can be
used to keep a small portion of
water unfrozen, or you can drill
1/2 in. holes along the length of
a piece of 4 in. PVC pipe and
sink it at the deep end with 4 in.
of the pipe extending above the
water surface.
If you have an unexpected
freeze, you can repeatedly
place a hot pot on the ice until
it melts a hole (keeping control
of it so that it doesn’t sink!).
Don’t hammer on the ice to
make an opening because the
vibrations could kill the fish.
Water Color
The color of the water is
significant. If your pond is
healthy, the water should
actually be amber rather than
clear, indicating the presence
of beneficial organisms. Green
water indicates the growth of
algae and is normal during the
first few weeks after filling the
pond.
The fish and submerged
plants will help the pond come
into balance. Brown water is
due to particles of sediment
stirred up by the fish, or by
strongly moving water. This
can be reduced by removing
some of the debris which has
settled to the bottom.
Black water means that tree
leaves are decaying in the
water, and they need to be
removed since they can release
toxic gases.
Decaying water lily leaves can
leave a film of oil on the
surface which can be removed
by placing a sheet of
newspaper on top of the water
and then pulling it off. If the
water has a white, cloudy
appearance, look for and
remove dead fish or other
animals which may have
drowned.
Types of Plants
There are several kinds of
pond vegetation. The most
common are submerged plants,
marginal plants, water lilies,
and floaters. As a general rule,
“...a small informal wildlife
pond can be accommodated
in most gardens, as it is the
natural population rather
than the pond itself which
is the main attraction."
– The Rock and Water Garden Expert
Dr. D.G. Hessayon
