Page 308 - Encyclopedia of Aquarium and Pond Fish, 3rd Edition

306 POND FISH: SETTING UP THE POND

Pumps and filters

Garden ponds are often stocked with many more fish
than would be found in a natural pond and so benefit
from the addition of a filtration system to improve
water quality. This is especially true for koi ponds,
where crystal-clear water is desirable to give the best
view of the colors and patterns of the fish. Filtration
systems are driven by electric pumps, which can also
be used to create fountains and water features.

Pond pumps fall into two main categories: submersible units
that function underwater, and powerful surface pumps for
use only in a dry location. Submersible pumps are generally
smaller and often run on a low voltage so are most suitable
for smaller ponds, while external pumps for larger ponds and
extensive water features usually run off household electricity.
To work effectively, a pump must have sufficient capacity to
cycle all of the water in the pond in two hours, so calculate Fountains are not simply decorative features but also improve
oxygenation of the water. The cascade should be chosen
the volume of water in the pond before choosing a pump. carefully, to ensure that it does not spray outside the pond.
Preformed pond units often have their volume marked on the
base; alternatively, when filling the pond, measure the volume be pumped under high pressure but at a low output, whereas
by attaching a flow meter to the hose. for the operation of a waterfall—where the water needs to
The choice of pump also depends on its intended function. be pumped uphill—a high output from the pump is required.
For example, when operating a fountain, the water needs to Refer to the manufacturer’s instructions and get advice from
reputable retailers to be sure that the pump you choose is
suitable for your intended use.

OUTDOOR ELECTRICITY Maintaining water quality
If you need to run an electrical supply from the house to the pond, Most filtration systems use separate pumps to draw water
hire a professional electrician, who will install cables in accordance from the pond and through the filter, although pumps with
with local building safety codes. Devices running directly off the an integral filter are also available. There are two main types
main supply must always be connected via a ground-fault circuit of pond filter: internal units, which sit underwater in the
interrupter (GFI). Low-voltage pumps, suitable for small ponds, do pond, and external filters, which are sited outside the pond.
not present a hazard and need not be installed by an electrician.
All filtration systems function in a similar manner (see box,
A low-voltage pump is operated by a opposite), but the filtration media they house varies. When
Transformer inside power supply of, typically, just 24 volts, installing an internal filter, locate the pump as close as possible
house reduces simply achieved through an indoor
the voltage transformer in the home. to the filter unit, to maintain the flow rate. By contrast, if the
Electrical Submersible, system uses an external filter chamber, locate the pump as
cable low-voltage
Plastic conduit pump in far as possible from the filter outflow, to ensure that clean
the pond water is not simply pumped straight back through the system.
Ultraviolet systems, located between the pump and filter,
External
wall of are a further refinement that can be used to achieve very high
house
water quality. Ultraviolet radiation emitted by the unit causes
algae in suspension to form into clumps, which are then easily
strained out of solution by the filter.

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