Ornamental Fish Ponds
one of publisher and bookseller InfinityJunction.com's ultra-mini guides to petcare
by the Infinity Junction editor in chief, Neil Gee
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In this article -
1 - the Peace of Ponds One of the nicest
things on a warm summer evening is to sit in dappled shade of surrounding
vegetation and just gaze and contemplate beside an ornamental fish pond. And
if the pond has colourful fish, a tinkling waterfall and nice plants
surrounding it, it's easy to find oneself transported away from the bustle
and stress of modern life into a world of tranquillity and peace. So, to
invest a few hours setting up and maintaining a pond in your garden, or on
your terrace or patio, is often well worthwhile. And if you do it right, it
won't be that awful mess of green slime you sometimes see in city gardens,
instead it will be a centrepiece to admire and be proud of.
Starting from Scratch - (think first) Assuming
you don't have an estate of acres and staff to match, don't be
over-ambitious. A pond of just a couple of hundred gallons (1000 litres) can
look terrific in a typical town garden and have a healthy ecosystem too.
And you don't need to dig it very deep or raise it very
high: a pond of 40cm (16 inches) is sufficiently deep for small and medium
sized fish, water lilies and many other attractive aquatic plants. Indeed
for marginal plants such as cotton grass you would need a shelf around part
of it much less than this, typically only 4 inches are needed (10cm) -
however if it is deeper it will give you a wider choice of plants, but
you'll have to raise bog garden plants on a brick or similar so as not to be
SAFETY WARNING: ponds, especially sunken ponds, are not
a clever idea to have in your garden when there are young children around.
It is possible for an adult to drown in just 2 inches (5cm) of water, so it
must be even less for toddlers, and infants often have no idea of what is
dangerous and what isn't.
2a) - types of pond
There are two most common types of domestic garden ponds-
those with a pre-formed 'hard' moulded liner, and those lined with flexible
butyl rubber. These days it really isn't worth building a cement lined pond
because it can take a bit of effort to stop it leaking after it has set and
shrunk, and needs months of filling and emptying to be certain the lime
residues won't kill your fish.
For overall safety of
your fish, the pre-formed hard moulded types are more reliable as it's much
more difficult to puncture and spring leaks. Yes they cost a bit more, but
it's worth paying the extra. Both these types need to be placed in a thick
layer of soft sand or thick old carpet inside their containment to ensure
they can't be squashed against sharp stones etc when filled with water.
2b) - where to
site a pond
Fish ponds don't like to be in permanent
full shade because the oxygenating plants cannot get enough light to do
their necessary job. But it also isn't good to have too much sunlight
because it tends to encourage algae to bloom and this can have a detrimental
effect both on the health of the ecosystem and the appearance of the pond.
Now, you can get around full sun by planting shrubs nearby or constructing
trellises or pergolas to provide partial shade in summer when plants come
into full leaf and when the pond needs most shading. You can also employ the
use of shade-providing aquatic plants- however be aware that, in temperate
latitudes, most ornamental (exotic) water lilies etc do not come into full
leaf until after the main season for the start of algal bloom has started.
2c) - raised or sunken?
Sunken ponds look more
natural and are often cheaper to build, however they are also much more
likely to get contaminated by muddy rainwater, dead leaves, drowned animals
and the like. Raised ponds need a strong enough structure to support them
and may not attract frogs etc, (if you want that,) unless there is a
vegetated ramp etc or they are built into a sloping bank where only part of
it is raised.
There is one major advantage of raised
or partially raised ponds and that is you don't have to be reliant on
expensive submersible water pumps to circulate and filter water. If you use
a hard liner, simple domestic plumbing can be used and an ordinary central
heating pump bought at only a fifth of the price for equivalent power. They
last just as long if installed in a suitable weather-proof housing and are
much easier to get at for maintenance. (NOTES- 1: you cannot use a standard
rotary water pump above water level because they need top pressure to work.
2: if you pierce the liner, do not do so right at the bottom in case your
joint leaks; an intake to the pump, such as the fitting used to fill a
lavatory cistern, should leave enough depth of water beneath it so that fish
can survive after seal failure. 3: a grid or mesh filter on the water intake
will stop baby fish, tadpoles etc from being sucked in and also protect the
pump's internal rotor from damage by debris.)
2d) - moving or
With very few exceptions, smaller ornamental
fish ponds should have some sort of water movement, either natural from a
stream, or more likely via an electric pump, (see above.) This is even more
important if your pond gets a lot of sun, as this tends to encourage all
sorts of bacterial, fungal and algal growth some of which is undesirable.
Ponds less than about 100 gallons (500 litres) need water circulation more
than those twice the size or greater, simply because small ponds are
unlikely to support such a diverse ecosystem as would keep them naturally
Having a large volume of flow compared to the
pond volume, such as (for a 1000 litre pond) from a central heating pump or
decent-sized submersible pond pump has enormous benefit over the rather
pathetic fountains often purchased by inexperienced home pond makers. If you
can achieve a turnover of at least several complete water changes per day,
the chances of keeping your water clean and free from blanket weed etc are
many times greater than if it takes a week to circulate the whole pond.
Don't forget you'll need to clean your pump occasionally, so a way of removing it without the water escaping is needed from the start. The rotor housing of most pumps can be dismantled and the input, output, chamber and rotor should all be thoroughly cleaned and any hard deposits carefully scraped off.
2e) - pond shape and depth.
The actual shape of a pond doesn't matter much, except fish can escape from predators easier in a pond which is not too long and narrow. To avoid land animal and bird predators the pond also needs some depth. Ornamental ponds should not be too shallow for aquatic plants to grow well. Also ponds that are too shallow tend have high light levels and can warm up so much that algae growth is encouraged- see further below.
2f) - filtered or natural?
A good idea with smaller
fish ponds is to include some sort of filtering for the water. The filter
can do a number of vital things - firstly it allows bacteria, which break
down fish faeces and other contaminants, to work vastly more effectively
than they could do in a static pond. Secondly if combined with a waterfall
or similar, it allows potentially poisonous dissolved gases such as ammonia
and carbon dioxide to escape into the air and additional oxygen to be
absorbed when its level in the pond water is low.
size of filter needed depends on your pond conditions, including how many
fish you expect to have and the flow rate of your circulation system. Large
expensive filters are not usually necessary for small domestic ponds with
just a dozen small fish, indeed you can often improvise a filter from a
large plastic container and basic filter medium which by itself is not
expensive. Don't forget that smaller filters need to be cleaned more
often. If you find your filter clogging quickly, then the water is too contaminated with solid matter and the bottom layer of water needs to be syphoned or pumped out along with most of the muck. As long as you don't take out more than 20% of the total volume in any week, then clean (tap) water can be run in without harming fish, (assuming the temperature difference is not great and the water not over-chlorinated.)
A new pond would do well to have
pre-conditioned filters installed; these are laced with useful bacteria and
can get your bio-filter off to a flying start. Alternatively, if you know
someone who already has a successful pond filter running, you could ask them
for a small piece of their filter material in exchange for a new piece and
place this in with your new filter to 'seed it' and speed the process of
seasoning the filter.
back up to topponds can attract wildlife - frogs and many other species, like
this blue dragonfly
3 - Sorting Out a Neglected
Pond You bought that house you fancied; it's got
a pond; it's all clagged with blanket weed or you can't see any fish through
brown murk, even though the sellers said there were some. What do you
Basically it's salvage what's worth having and
chucking out everything else time. Start siphoning or bailing until you come
across pots of plants, submerged pipes, fish or whatever.
The fish should be caught using an aquarium grade net
(fine soft mesh) and put in a very large container of pond water. Over a
period of days, (not hours,) you can replace no more than quarter of this container's
volume with clean (best un-chlorinated) water, which must be at a similar
temperature, once or at most twice a day, until the water is completely
clear and you can examine the fish. If you have an aquarium air pump, bubble
the water to keep it moving and oxygenated. Feed the fish with goldfish food
or similar while they are in the transitional tank. If you see any sign of
disease, treat it accordingly and do not put the fish back in the pond
unless completely cured. Seriously diseased fish should be isolated from the
others in a separate tank.
Pond weed should be
discarded if straggly or badly covered in blanket weed. (CARE- some types of pond weed can kill other plants if dumped on top, bin it or give it away to another pondy, don't leave it on the lawn for long.) Water lilies should
be rinsed thoroughly and freed from all other weed and contamination, dead
leaves cut off and then the lily must be kept wet (not just damp) at all times. If this is
done in winter and the corms are large and sprouting in more than one place,
then the corm can be cut or pulled apart to make new plants. Lightly
contaminated aquatic plants of all types can be rinsed, blanket weed pulled
off by hand during the process, and then placed in a bucket or tank of pink
potassium permanganate solution for an hour or so. (If you accidentally add
too much permanganate and it goes purple, only treat the weed for a few
minutes, then place in clean tap water - do not let it dry out. Keep
oxygenating weed in clean water, in sunlight to get it growing until it goes
back in the pond.
Drain the pond entirely, brush
obvious growth off the sides and swill it out with clean tap water a couple
of times, taking the last dirty water out with a sponge or similar - do not
use disinfectant, bleach, or other cleansers as they can cause long-term
If the pond had a filter this should be
emptied and the container roughly cleaned without chemical cleansing agents
and allowed to dry out. The filter medium should be squeezed empty of water
(but not stone dry,) if badly clogged it should rinsed and teased into an
open structure, then left outside in shade (unless freezing) to oxygenate
for a few days depending on temperature, preferably a couple of weeks in
winter; this will kill unwanted anaerobic bacteria, which can cause a pond
to go foul with poisonous hydrogen sulphide. You should be able to use it
again to 'seed' a new filter with useful bacteria. All pipes, pumps and waterfalls
or fountains should be emptied, cleaned and dried as best as possible..
Now go to the next sections...
Coming in the next
few months from Infinity Junction: The Pond Builder by Neil Gee - a very
different slant on pond building! (A black comedy.) Check the book list at Infinity
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4 - Starting a New Pond - actually doing it You've got a stable and level-edged pond liner
nicely bedded-down in thick protective sand in a good, safe position in your
garden. Yes? If no, then get it before you go any further.
If you are going to keep fish, in the deepest part you
need to make a hiding place for them to escape to, eg from cats, bird
predators etc. This should be large enough and stable enough to be a truly
safe haven. Old ceramic drain pipe laid on its side often suffices, and if you can find
square-section type, (like old fashioned chimney liners,) this will also allow you to place potted marginal plants
on top of it, if not too deep.
Set up your water
filter and circulation system taking care to follow safety instructions, and
also your waterfall or fountain if employed.
where you will later put plants, preferably potted, and make sure the depths
are right for each plant. Checking this before you fill the pond, with the
same size pots you expect to use, will save time and trouble later. Do any
finishing work such as edging stones etc before filling so that the water
can't get contaminated with mortar etc. Clean up dust and dropped excess
material carefully, leaving the pond liner uncontaminated.
When you have sorted everything that's going to be too
deep to fix later, or at too long a stretch to do without wading, then you
can fill the pond. Ideally you would use un-chlorinated sterile water, but
since such a thing is usually unobtainable in the quantities you need,
just use chlorinated tap water and leave it circulating for at least a week,
(longer in cool weather,) before introducing plants. During this week you
can adjust the waterfall to get the most pleasing effect, both visually and
the sound it makes. If you use lights, you can also adjust them at the same
5 - Plants One of the best methods of coping with pond
plants is to keep them in pots: that makes them much easier to move around
or bring out of the pond for trimming of dead stems and leaves, etc.
Oxygenating weeds that grow proper roots (most of them do) are best potted
into soil, (not compost or peat,) but to stop the soil turning the pond
cloudy, a dense layer of moss can be used in the bottom where the holes are,
and a layer of heavy pebbles placed on top around the stems. Don't use
aquarium sized filter shingle because fish will move the little stones and
disturb both soil and roots - something in the region of 2cm diameter
(approx one inch) or even a bit more would do.
good oxygenator, which is also both common and pretty tough once
established, is elodea - 'Canadian pondweed' variety is the toughest. Plant more than you think you need to start off with
because fish have a habit of uprooting it until its root system is properly
grown. It's hard to have too much of it and you can always cut it back a bit if necessary.
Larger plants such as water lilies sometimes develop pretty big root systems, well beyond
their original pot, and these can be covered in a layer of soil, in turn
this is also covered with stones to stop fish disturbing it. Until fish
start to fertilise plants naturally, purpose manufactured slow dissolving
(low nitrogen) solid fertiliser pellets can be used, but sparingly: you
don't want the chemical content to be unpleasant for fish or cause unwanted
In a temperate spring, water-weeds need
at least a couple of weeks to get over the shock of being re-planted, and
ideally a whole month to establish themselves and be strong enough to resist
the curiosity of fish.
Floating plants can also be
useful for reducing light levels in a pond and thus helping to keep algae to
a minimum. There are many dozens of varieties from humble duckweed, through rampant
water hyacinth, to brightly coloured salvinias, (pictured.) (Last two not
hardy in cool temperate climates, so keep some in a bucket indoors to
over-winter.) And there are varieties of plants which don't permanently root, but sink
in winter and float just beneath the surface in summer; such as hornwort.
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6 - Algae and Blanket Weed The bane of many a pond owner
are various forms of algae. Two of the worst are that green/brown bloom
which swamps a pond in certain conditions and makes it so murky that you
cannot see your own finger when submersed, and the dreaded blanket weed,
which ties up everything with millions of tiny green strings. The problem
is, once well established it's very difficult to get rid of blanket weed without hard work. (See further below for suggestions.)
Algae like warm water, sun, and plant fertiliser. They don't like a very highly oxygenated water. Keep the pond sufficiently shaded and the algae cannot thrive, one way is to let water lilies grow big enough to create natural shade. Also allow your oxygenating weeds to grow really bushy and spread out: as soon as the sun shines they'll start killing free-floating algae. Just make sure there are plenty of free passages for fish to swim around.
Avoid having a pond right next to a warm wall or in hot sunlight. Once your plants are growing well, reduce nitrogen and fertilising minerals, if necessary by a slow water change.
There are various algae killing agents, but experience shows that some of these cause as many problems as they solve, for example those based on permanganate and a
flocculating agent, leave a thick foul sludge in the bottom of a pond which must be removed for the safety of your fish. One of the safest ones which actually does anything useful is dimethylurea, often available in mineral blocks which dissolve slowly. This too can cause a sediment, but not so rapid nor so foul. (Note: blocks containing dimethylurea should be of recent
manufacture as they becomes less effective with age.) The earlier you tackle algae, the easier it is to control - as soon as any sign of green or brown cloudiness appears, treat the pond.
Do not put fish into a pond with very high algae concentration because at night the algae can starve a pond of oxygen.
Blanket weed is most effectively reduced by pulling it gently out by hand, trying not to pull up the wanted plants. It needs to be done regularly because it can restrict the movement of fish and if really bad can even trap them - get your arms wet! For areas you cannot easily reach, or if you don't want to dip your hand in the pond, get a straight stick and cut a groove in the end. It should be light and as long as is convenient, with the prong tips very roughly 2cm apart, (1 inch,) and with a clear gap at the ends of about 1 cm, then it can be used to penetrate the blanket and then slowly wind it round and round until it is caught. Lift or pull it out carefully to avoid uprooting or breaking wanted plants. You can go on doing this for hours in a big pond- some people find it therapeutic; the pond certainly will. By the time lilies and other light-shading plants have grown, you'll have to do this this less and less.
Only if your pond has no fish, you can help reduce algae by using a special black dye to cut down sunlight. This also makes the contrast between water and floating/marginal plants seem greater but will reduce submerged plant growth and can harm wildlife.
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7 - Fish
Most important - don't be impatient and put fish in your
pond before it's free from chlorine and all building residues, the water
must be clean and the plants bedded in securely and producing oxygen in
There are dozens of fancy fish breeds
available in aquarium shops and pond centres. Unless you really know what
you are doing, stick to the resilient old favourites. For the climate here
at Infinity Junction (north-west England) red comets, shubunkins and orf are
pretty tough. Fancy carp will also survive, but since these tend to be
pricey to buy, you would be better to get your pond set up and thriving for
a couple of years before you try them.
And then there
are bottom feeders etc. To be honest, you really need a largish pond and to
have a bit of experience before using these.
8 - Food
After some months, a larger pond may supply fishes'
nutritional needs from its own ecosystem. However, it's more fun to feed
them and watch them come up to the food. If you want this to happen, you'll have
to feed them a little every day until they get into the habit. Depending on
the size of fish, you can use ordinary goldfish flakes or pond-fish pellets.
Don't give them too much at once because food may go uneaten and start to go
rotten in the pond. Fish really do better with occasional live food, in a
large well established pond you won't have to worry, but in a newish pond,
occasional bags of daphnia etc will help keep fish healthy.
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9 - Winter In cool temperate climates ponds usually
go inactive during the coldest winter months. Depending on the type of fish and the
amount of daylight shining on the pond, very roughly when the water (not air temperature) drops
continuously below 8°C the weed will stop growing and the fish stop feeding
actively. You still need to monitor the pond for various reasons. First,
fallen leaves can form a stagnant layer at the bottom of the pond, which if
left for long can rot and produce very toxic hydrogen sulphide gas which
kills fish and other animals. Remove as much leaf debris as you can in
autumn, including sunken lily leaves. Second, ice can form on top and if
left for long can allow build-up of poisonous gases and not allow sufficient
oxygen into the water for the fish to survive. Leaving the circulation pump
running will help, but even then you may need to help it by taking an inch
(2cm) of water out from beneath the ice layer, and carefully puncture a hole
or two to allow air to get at the water surface. Third, sudden winter warm
spells can make fish hungry, but with no food supply they might
starve - try feeding them a little, if they take it, feed a bit at a time until they lose interest. Try this every day when the weather is mild.
Do monitor fish regularly: at lower temperatures, if any do get ill, their metabolism is
often too slow for their own immune response and physical healing processes
to work properly. If necessary bring injured or sick fish into a slightly
warmer environment to treat them, eg a tank in your garage.
Winter is also the time to check water plants and remove blanket weed. Cold weather often has a clearing effect on small ponds: algae and bacteria grow too slowly to be a cause of cloudiness. It makes it easier to see what you're doing. Also splitting or transplanting is much less harmful when plants are dormant.
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Further Suggestions 10a) - Have your pond
overflow into a separate bog garden at the water's edge; the choice of suitable plants is
enormous, from giant dark red lobelia, through a host of fancy grasses,
(cotton grass pictured,) rushes and even could include delicious wild
strawberries just above water level. Don't forget to top up pond water levels
to keep the bog garden wet.
10b) - If you suffer from
cats or herons trying to get your fish, lay green synthetic netting,
or string brightly coloured cotton thread over the pond when you're not
there. You can support it on a simple bamboo framework if not too big, or
hook it onto anchor points around the pond - being dark green, you'll hardly
notice netting at a distance. With smaller ponds, you can use tall pampas flower stems stuck into the ground to make landing impossible for herons.
10c) - Plant a
wind-break or visual shelter around your pond, possibly with an opening out
of sight of the neighbours, to make the pond area into your secret den.
10d) - Buy or make yourself a comfortable outside
chair or bench, not one of those cheap back-breakers, a really comfortable
one. Put a small table or ledge somewhere nearby and sit there with your
glass of wine, ice-cold beer, mineral water, or whatever else you fancy. Just
forget the telly and the office and dream your own dreams. If
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* Duckweed, very small but frequently numerous pale green leaved plants, can be a nuisance because of the rate at which it can spread and cover the whole surface. Many pond owners hate duckweed. If you need to get rid of it, this is a long job unless you start your pond afresh. The best way to get rid of it in an established and otherwise healthy pond is to take all potted and marginal plants out because they can harbour duckweed without you realising. Hose these down with water on land that won't drain into the pond. If you do this in cold weather (eg a temperate winter) you can let it dry out a bit which will help kill any remaining duckweed around the roots and lower stems- DON'T let water lilies dry at all or you'll kill them. When ice forms, sheets of trapped duckweed can be lifted out then removed. You won't get it all out like this but it sure helps. Then you can use aquarium nets to lift duckweed plants that are not attached to other plants. After that it's a very tedious job of picking the rest out by hand. You can spread this over several sessions, gradually clearing area by area. Even after that you'll find some has managed to hide itself amongst other plants etc, so you'll need to be vigilant for quite a few days after the last visible duckweed plant appears to have been removed.
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