how to construct concrete pond

Although concrete pond is now less
commonly used to build ponds
than it once was and certainly
makes more demands on the
builder than the alternatives, it
does have some definite advantages which still make it a
material worth considering.
Particularly when it comes to some
kinds of more specialist water
features – especially those needing
vertical walls such as traditional formal or koi ponds – there is not
much to match the strength and
rigidity of concrete. In the days when concrete was
used extensively for pond
construction, the standard method
involved pouring the mix into a
mould made with wooden
shuttering. While this method allows for irregular shapes to be
created, the concrete is prone to
cracking and the rise of much
cheaper liners and pre-formed
ponds has almost entirely
superseded this approach for “natural-look” water features.
Most of today’s concrete ponds
are built using breeze blocks, which
are then skimmed with a sharp
s and/cement/fibre glass mix. Starting the Construction The construction process for this
type of pond is relatively straight-
forward, if some what time-
consuming. The first step is to dig
out the hole to the required size;
since most concrete ponds are square or rectangular, it is worth
taking the time to mark out the
outline making sure that the angles
are true, the lines are straight and
the walls as near upright as
possible. Getting this right at the outset can save a lot of time and
frustration in the long run since as
the digging progresses, it can be
surprisingly easy to drift off
course You should aim to go down
around 5 - 6 inches (12 - 15cm) below the finished pond's intended
depth, to allow for the base. Once the excavation for the actual
body of the pond is complete,
you’ll need to dig a trench for
the foundations – about 4 inches
(10cm) deep and 8 inches across
(20cm) – around the outside of the hole to support the block-work.
Once this has been completed, it
needs to be filled with concrete and
then allowed to dry thoroughly. Next, the soil at the base of the
hole should be raked level, a layer
of sand added and then tamped
down firmly to compact it well,
making sure that it finishes level
with the foundations. Lay a 3inch (7.5cm) coat of concrete over the
whole area and allow it to dry
completely, before adding
galvanised mesh for reinforcement
and then finish off with a second
3 inch (7.5cm) layer of concrete. Make sure it has dried out
thoroughly before continuing. The
whole base now needs to be
skimmed with a half-inch (12mm)
coat of cement containing
reinforcing fibres. The purpose- made reinforcement fibres are
designed to help prevent small
cracks from appearing and makes
the whole structure less likely to
leak; they can be bought from
most builders’ merchants and specialist water garden suppliers. After 24 hours, once the cement
base has had a chance to dry, the
next step is to build the block-work
walls, filling both the hollows in the
blocks themselves and any gaps
between them and the surrounding soil with concrete. A
course or two of house bricks at
the top of the block wall finishes
the whole thing off neatly,
providing a level edging for the
pond. Finishing Off Your Pond The walls need to be left to dry for
at least another 48 hours, after
which time they can be dampened
slightly and then skimmed with a
half-inch (12mm) layer of fibre-
reinforced cement to match the base. The final part of the real
construction work calls for an
edging layer of bricks or slabs to
be mortared into place around the
top of the wall, allowing an over-
hang of a good 2 or 3 inches (5 or 7.5cm). After a further 48 hours, the last
step is to paint the inside of the
structure with a good quality
water proof seal ant – principally to
stop the lime in the cement from
leaching out into the water and causing problems for the plants
and pond-life. Wait a few more
days and then fill the pond. It is
always a good idea to check the pH
of the water in a concrete pond to
make sure it is around neutral – pH 7 – before you start planting up
or introducing any fish; if the pH is
much higher than this, the
conditions will be too alkaline for
pond-life to thrive. If this does
occur, it doesn’t automatically mean that your attempts at sealing
the concrete have failed, so it is
worth waiting a few more days
and testing again as the problem
can sometimes be a short-live d
one. Building a concrete pond is
undoubtedly a far larger
undertaking than making one with
any of the more common types of
liner, but for some types of pond, it
remains the best material for the job. Although they take longer to
complete and require much more
in the way of effort, if you take your time and proceed carefully, a
very durable and good-looking
pond.

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