A garden pond, with the right planning and stocked with the right kind of aquatic plants and fish, will be a marvellous asset to your garden, attracting a great many wild animals and eventually becoming a miniature nature reserve. It is possible to have a pond which is self sustaining, requiring only the occasional maintenance to keep it in good condition.
The Size of the Pond
A very large pond is often difficult to access and you have to keep in mind where
you would put all the water if, for any reason, it had to be emptied and, how
would you do it? On the other hand, a very small pond may require constant
attention as it may not be large enough to sustain itself.
A garden pond does not have to be too deep and should preferably have a shelf
about 12 “below the top of the side, to site aquatic plants. If you are digging the
pond to your own design and intend to have no fish, or only goldfish, or orfe, it
needs to be no more and no less than 2′ 6” at its greatest depth. However, if you
are keeping Koi, you will need a pool depth of 4ft, but remember deep ponds can
be difficult and dangerous to clean out.
Where to site the Pond
Try to site your pond in a position away from trees, as autumn leaves that fall on
the pond will rot and foul the water. Where this is not possible, you may have to
net the pond when the leaves are falling.
Bear in mind that rotting grass clippings in a pond are as dangerous as leaves,
so you need to consider how near the lawn the pond is going to be, or how
effective your lawn mower is in picking up the grass.
Ideally, a pond should have some shade rather than being in full sun all day.
If you are going to run a pump, you will also need a source of electricity.
Constructing the Pond
There are many ways to build a pond, the most common being pre-formed
purchased form a garden centre, the size of which may be determined by the
kind of transport available to get it home. Whilst a pre-formed pond is a ready
made pond, a great deal of accuracy is required in digging the hole, getting the
pond level and back filling with the soil you have taken out. Get it wrong and the
pond will leak water at one end and mice and other vermin may find a home in
the spaces between the soil and the pond sides.
An alternative method is to construct a pond to your own design, using a flexible
liner made of Butyl, or a strong plastic. You must however, make sure there are
no stones protruding from the pond sides that could puncture the liner, indeed it’s
a good idea to place a layer of damp sharp sand against the sides, before you
place the liner ready for filling.
The third method is to dig out the shape of the pond, then set concrete at least 2″
thick. This should be a permanent fixture on a clay soil, but can crack and leak
on soft sandy soils. Furthermore, a period of time needs to elapse before fish
can be released into a concrete pond as they are affected by the lime from the
concrete base that can seep into the water.
Never use polythene sheeting as it becomes brittle and will leak in no time at all.
Water in a new pond will be green for up to four weeks until the water becomes
If the soil you take out of the pond site is of reasonable quality, you can spread it
around parts of the garden, or perhaps form it into a heap for a small waterfall.
You should leave it to settle for a few months before doing this.
Ponds do not have to include fish, or even plants, but a pond without one or the
other would be pretty boring and become stagnant in a matter of weeks if the
water remained still. However, make sure your plants are established before
adding fish to the pond as initially the fish want somewhere to hide. Until now
they have never been in anything bigger than a fish tank and being transferred
into a garden pond must be rather traumatic.
Always buy your fish from a reputable source. Never accept fish from friends or
neighbours as they may have a virus which may in turn infect your fish. Goldfish,
Orfe and if your pond is large enough, Koi, and many other types of fish will
survive a British winter in a pond even if it freezes over. Refrain from buying
Tench as they are bottom feeders and while they eat up the food which drifts
down from the surface, they continually disturb the bottom of the pond and
discolour the water.
How many fish
There are all kinds of formula for calculating the numbers of fish for a pond and
some can get quite complicated. A simple formula is to measure the surface of
the pond and every square foot can accommodate half an inch of fish. For
example, a 6ft x 4ft (24 sq ft) pond will maintain 24 x 6″ fish, or 48 x 3″ fish.
However, if you have the right conditions, your fish will breed, so it’s probably
better to start off with no more than half of your maximum quota.
For garden water features, garden furniture, ponds and water
feature accessories, Click here to visit an aquatics specialist.
Looking after your fish
When you buy fish, they are normally in half filled plastic bags. Float the bag in
the pond for at least 30 minutes to allow the water temperatures to equalize
before releasing the fish.
Feed your fish daily with a proprietary fish food. You can feed fish twice a day
during the summer months, supplying them with only enough food that can be
eaten in 10 minutes. Do not feed them after October, or before April. Fish
metabolism slows down in cold water and they do not feed, or move around
much during the winter months, merely surviving in a state of dormancy. Any
feed will fall to the bottom of the pond and foul the water. However, on a warm
winter’s day, fish can start moving around and take in feed if it is given to them.
This is dangerous as the digestive system of the fish can’t cope if the weather
turns cold again.
Fish can suffer from a range of ailments, including parasites, fungal infections
and fin rot. You can buy proprietary preparations to treat these problems from
most reputable pet shops that deal in aquatics.
There are several distinct groups of plants you can grow in or around a garden
pond. Unfortunately, there are too many to list here, so you should ask at a
garden centre dealing in aquatics for advice on the best plants for your pond.
Oxygenators are essential for keeping the pond healthy and clear and you should
always have at least one submerged to absorb carbon dioxide and release
oxygen into the water. They can multiply fairly rapidly and outgrow their space if
not cut back. Remove the excess, which makes good garden compost when
Water lilies are planted in containers that sit on the bottom of the pond and
produce leaves and flowers on the surface in summer. They also help to shade
the pond from the sun and inhibit the growth of weed. Don’t over plant, as they
grow rapidly: one is sufficient in a small pond.
Marginals are planted in containers set in shallow water on shelves around the
Floaters are flowering plants that simply float on the pond. Marsh plants can be
planted at the edges of the pond, if the liner is extended and filled with soil to
create waterlogged bog conditions.
Don’t use garden soil as it contains too many impurities and could contaminate
the water. Your garden centre will advise on the best compost to use.
Spread gravel around the top of plant containers as fish delight in rummaging
around the bottom of plants, disturbing the compost and discolouring the water.
The main problems in ponds are blanket weed, algae and fallen leaves.
Algae can be avoided to some extent by siting your pond away from the full sun.
It is less of a problem when the pond is established with oxygenators and lilies.
Blanket weed is a bigger enemy as it thrives in healthy water. It can be removed
by hand or with a stick, being careful not to puncture the liner. There are other
effective methods to remove blanket weed, such as floating barley straw on the
surface. You could also use chemicals, but the best method of cutting down on
blanket weed is to keep the water moving. If you have a fountain and/or
waterfall, keep it running at all times to aerate the pond. This will also keep ice
from forming across all the surface of the pond in the winter
Leaves are a menace and if your pond is near trees, then the only way to keep
the leaves out is to net the pond.
Ice rarely freezes in water beyond a depth of 18″ in the UK and providing there
are no rotting leaves giving off poisonous gas in the bottom of the pond and there
is a hole in the ice to allow in oxygen, the fish will survive quite well for several
months during the winter.
A rubber ball floating on the surface of the pond in winter can usually move
around sufficiently enough to leave a hole in the ice thus allowing oxygen to get
through, or use hot water from a kettle to make a hole in the ice. Never break the
ice as this will affect the fish’s nervous systems and can kill them.
If you have a pump, a filter fixed to it, will remove algae and other particles from
the water, although the filter will need cleaning on a regular basis.
With a larger pond, you can pump the water through a tank containing some kind
of filtration product, although clean gravel will also do the trick and a tank full of
hair curlers acts as an excellent filter. A central heating header tank for a small
pond or a cold water storage tank for a larger pond is ideal. Bacteria that remove
toxic waste will grow on the filters, thus keeping the pond clean and healthy.
If pollution remains a major problem, you can run the hose from the pump
through an ultraviolet light to kill the algae and totally eliminate green water.
If your pond springs a leak it may mean draining it down to where the hole is, or
draining it completely to affect a repair. If the latter is the case, move the fish and
plants to a temporary tank.
You can purchase pond puncture kits to repair plastic liners form a garden centre
that has an aquatics department.
A crack in a pre-formed pond is best fixed using a car body repair kit.
If you have a concrete pond, it’s probably better to drain it and add a plastic liner,
rather than point up with cement, which rarely works.
Within a very short space of time, your pond will attract frogs and/or toads and, if
you are lucky, newts. They will benefit your garden as all three eat slugs and
snails, so you should make it easy for them to get in and out of the pond by
having an angled slope to climb up. These reptiles will undoubtedly spawn and
you will need to make sure the spawn doesn’t clog up the pump filter. Various
insects, such as water boatmen, which literally walk on water, bees, butterflies
and hovering dragon and damsel flies will turn up as will water snails, which you
will need to control as they can carry disease.
Birds will be attracted to drink and bathe in fountains and waterfalls, but you do
not need a visiting heron! If this becomes a problem, you may have to net the
pond, or wind black or near invisible thread around pegs around the pond to
catch the herons’ legs as they try to wade in.
A good pond is hard to beat as a source of tranquility in the garden.