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20
WHY IS MY POND WATER
BROWN?
There are two types of “brown” water:
• Clear with a brown tint – the colour of a
cup of tea before you add milk;
• Muddy brown – like tea after you’ve
added milk!
If your water is clear but tinted brown, it is
likely to be tannins which have leached out
of leaves in the pond. If your pond has an
inflow from a peaty area this will also colour
your water brown.
If your water is a cloudy or muddy brown
(or grey) colour, then this is usually sediment
stirred-up from the pond bottom. The most
common culprits are fish, but sometimes
ducks and dogs cause problems. Some
new ponds can remain cloudy for weeks or
even months, whilst the bottom sediment
settles back down again, particularly where
the pond has a clay base. If your pond is
new and still settling down, it is best to wait
patiently. However, if the banks above the
water level are bare then it’s worth trying
to plant them up fairly quickly, for example
with a grass-mix, to prevent more sediment
from washing into the pond.
WHAT TO DO IF YOUR
POND DRIES OUT
People often worry when their water levels
fall in summer. However, in natural ponds, a
water level drop of at least 0.5 m is typical
in summer. These falling water levels create
one of the most biologically rich areas of a
pond – ‘the drawdown zone’.
You can let pond levels drop quite low
before losing any animals (except fish).
Most creatures, including tadpoles, will
be happy in just two to five centimetres
of water – especially if there are plenty
of plants or algae to keep the water
oxygenated.
Overheating may be a problem in shallow
ponds. If the water temperatures get to
over 35 °C (which is possible even when
air temperatures are around 30 °C), then
some animals, including tadpoles and
water slaters, will die. At this stage it is worth
topping-up.
If you have clean water ponds filled
with
rain water, and want to avoid adding
unwanted nutrients and chemicals to your
pond, what can you do?
• Use water from rainwater butts
to
maintain a few centimetres of water in
the bottom.
• Just let the pond dry out
– annual drying
out of ponds has been a natural process
for hundreds of millions of years. Many
creatures are specially adapted to cope
with it, and the pond will recolonise quickly.