Fitting and filling the liner
Before you fit and fill the liner it is wise to decide how you wish
to finish the edge and where you want the water level to be. If you simply anchor
the liner down with paving slabs, the water will never reach higher than the bottom of the
slabs (as in diagram z-i) and when water is lost by evaporation
(sun, wind, etc.) it will be even lower, exposing the liner to view and to the damaging
effect of sunlight. This can be avoided by leaving enough liner to reach up behind
the slabs to ground level. The water level will then be able to reach as high as the
top of the slabs (as in diagram z-ii).The same applies if you
use turf instead of paving. Either way, you need to cut a trench the correct depth
for the edging as you will find it very messy to do this after the liner is filled with
Once the hole and the edge are correctly shaped and padded, drape
the liner across the hole. This will be much easier if you pick a sunny day and lay
the liner in the sun until it is warm and flexible (and if you do it with a friend).
If you are using butyl it only needs to sag loosely into the hole because it will
stretch into the nooks and crannies as the weight of the water lying on it increases.
Anchor the edges of the liner with bricks or other objects heavy enough to keep it
taut and prevent it falling into the hole. Put your hose onto the liner and
keep watch as the water moulds it to the shape of the hole. You will need to move
the weights around to allow the liner to creep where it needs to. Once the pond is nearly
full, turn off the water and trim off surplus liner, being careful to leave enough to
complete whatever edging you have planned.
with your pond
Once you have decided on and created your first pond, the next
priority is keeping the water transparent and providing vegetation for decoration and to
feed, oxygenate and hide the wildlife. This is all achieved by the correct balance
My first pond was filled in early spring to receive the spawn
offered in the newspaper. It soon dawned on me that it would be quite a few years
before the frogs resulting from this spawn were big enough to eat the gigantic snails
already dominating my garden. But I was just in time to find two pairs of frogs and
one pair of toads all purchased in amplexus1
(this is no longer legal) soon to spawn. A few water plants were popped onto the
shelf, some bunches of oxygenators were submerged and by early
summer I had bought a few fish and the water was like thick pea-soup! This happens
to all new ponds and is very frustrating because you can no longer see the tadpoles, fish
or the interesting insects that rapidly arrive from nowhere to live in your pond. The
green soup consists of tiny algae floating in the water and these algae will colonise any
water left standing in light conditions. If you do not believe this, leave a clear
glass of tap-water on a sunny window-sill for a few days.
Try very hard to be patient with green water. I was impatient
and treated the first pond with algicide which did indeed kill the green soup but a few
weeks later it was back with a vengeance. The original algae were killed by the
algicide and sank to the bottom as debris. Organic debris is food and any surviving
green algae now had a much improved supply of food to produce the next even stronger
generation of pea-soup. The secret is patience and the correct balance of
plants. Like any other green plant, algae need light and food (nutrients).
They can be deprived of light by leaves that spread out over the surface, and growing
water lilies is a very attractive way of doing this. The lilies and any other growing
plants use up some of the food, and submerged plants (often called oxygenators) provide
further competition for the food. Even blanket-weed, another type of alga, is a good
oxygenator and nutrient consumer.
Another cause of green water is the presence of fish, especially if
you feed them, because their excretions increase the stock of nutrients available for
unwanted algae. If you do not feed them, they tend to eat anything they find
including tadpoles, dragonfly nymphs, and the early stages of other insects. This is
mentioned again under "Fish or no fish"..
Once algicide had proved an expensive mistake in the first pond, I
bought a water-lily (see Pond-plants) and some untreated cork tiles which I floated on the
surface to provide shade while the lily leaves grew. This worked well and I have
never used algicide again. When I filled pond 2 for the first time I was ready for the
pea-soup with my collection of cork tiles, water-lilies and a new trick. I had a
pair of worn-out bed-sheets which were dark green (all the rage in the 1960s), and I
draped one of these across one end of the new pond so that with the cork-tiles, about 60%
of the surface was covered. This combination worked so well that pond number 2 never
developed the algal pea-soup. By its second summer, the water-lilies had established
enough to manage without cork or sheet.
Water-lilies and other water plants are ridiculously expensive to
buy from shops. Most people who have ponds, have water-lilies and other plants that
grow too big quite quickly so, before spending a lot of money, get to know which
neighbours have ponds and offer to take surplus off their hands at pruning time
(throughout the summer for most plants). Once your pond is established, you may want to be
a bit more selective about the size and colour of your lilies (I am not crazy about those
huge pink ones that look like plastic replicas) but while you are getting the water sorted
out, a lot of free lily-pads are ideal.
Plants for the bottom (75 cm deep): Water lilies, Water
Hawthorn (Aponogeton distachyus), oxygenators (see below).
Plants for the shelf: Flowering Rush (Butomus umbellatus)Bog
Arum (Calla palustris), Marsh Marigold (Caltha palustris), Bog Bean (Menyanthes
trifoliata), Fringed Water-lily (Nymphoides peltata), Monkey Flower (Mimulus
guttatus), Pickerel Weed (Pontederia cordata), Arrowhead (Sagittaria
sagittifolia), Reed Mace (often incorrectly called Bulrush) (avoid the bigger ones
and go for Typha minima), Brooklime (Veronica beccabunga), Water Mint (Mentha
aquatica), Irises, Crowfoots and Spearworts.
Floating plants: Water Fern (Azolla filiculoides).
Oxygenators: Rigid Hornwort (Ceratophyllum
demersum); the very popular Canadian Waterweed (Elodea canadensis) is an
Aliens (in UK): New Zealand Pigmyweed (Crassula helmsii),
Parrot's-feather (Myriophyllum aquaticum),
In the plant table (Plants for UK Ponds) there are lists of plants
indigenous to the UK that thrive in different parts of the pond. You will find many
other enticing and exotic ones on sale at nurseries but be wary of things that will not
survive local weather and of "aliens". I am using this word to refer to
plants that are imported from outside a country, which if they escape into the countryside
will compete with and damage or destroy local species. Apart from the fact that this harms
biodiversity (e.g., local larvae will not be able to eat the leaves), there are now a few
which it is illegal to introduce into the wild: in the UK Parrot's-feather, New Zealand
Pygmyweed, Japanese Knotweed and Himalayan Balsam. It is better for your own local
biodiversity to stick to locally successful plants.
A few pretty goldfish can bring life and grace to your pond,
watching them grow and learn to come for food can be fascinating, and I had always enjoyed
having fish in my ponds. However, there is a price to pay and I proved this to myself with
my third pond. When I was obliged (by leaking) to empty it, I had been wondering for
2 years why there were so few dragonflies emerging when I had seen with my own eyes many
Southern Hawkers, Emperors and other species laying eggs in and near the pond.
I had acquired half a dozen goldfish, four Golden Orfe and a couple of Green Tench.
They all seemed to be thriving and growing and I thought that I was protecting the
wildlife by supplying them with bought fish-food .
During the clearing of pond 3, every single bucketful of water was
scrutinised and sieved in order to save and replace such things as dragonfly and other
nymphs, water fleas, boatmen, back-swimmers, newts, etc. There were very small
numbers of everything and in particular only 3 dragonfly nymphs. I decided that the
fish must be the culprits, simply eating everything that moved. A neighbour with a
much bigger pond was happy to adopt them, otherwise I would have asked a nursery to take
them, as exotic ("alien") fish should never be introduced into wild ponds,
lakes or rivers. Four years later the water was seething with life and I was able to
watch literally dozens of Southern Hawker dragonflies emerging and flying away, so I think
the fish were indeed causing massive depredation.
A final thought about excluding fish. The presence of fish will
attract the attention of several predators including herons, gulls, kingfishers, mink and
otters (and, of course, domestic cats). As most of these will also eat frogs and newts,
you just have to make your own decision about who gets priority.