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Fresh and saltwater aquariums in education
Introduction
May both beautiful and interesting organisms inhabit the sea. People
have for a long time tried to keep these organisms in an aquarium.
It is a little more difficult compared with a freshwater aquarium.
This can be the result of many factors, such as; too many organisms
in too small a tank, too much feeding or too much organic material
that decays and causes oxygen deficency.
The aquarium
Sea water contains different salts.
These can affect many materials, mostly metals and furthermore many
metals in solution are poisonous and affect Marine organisms. A sea
water aquarium must therefore be constructed of materials that are
not affected by the water. For small aquariums, plastic containers
and tubs can be used.
The best aquariums are made out of glass that have been
glued with silicon glue that is suitable for aquariums. Most aquariums
these days are built in this way.
Avoid casted and moulded aquariums as they easily crack
and break. In the same way, aquariums with frames and other metal
parts should also be avoided as the saltwater corrodes the metal.
If a stereo microscope or a good magnifying glass is
available you can study organisms that are only a few millimetres
in size. To make them easier to handle under a microscope it is advantageous
to keep them in small glass dishes. These dishes can stand in larger
covered containers containing sea water.
Sea water
A sea water aquarium can be filled with ordinary sea water or "man-made"
sea water. The salinity along our coasts can vary greatly in surface
waters. There are many reasons for these variations, but one major
reason is the run off from estuaries and wet lands. It is therefore
important that sea water is collected so far away from such areas
as possible. Water can be collected and transported in plastic containers
and if possible kept cold and shaded. Make sure the containers are
tight. Sea water can also be stored, as long as it is kept cold and
in the dark.
It is also possible to produce sea water. In aquarium
stores it is possible to buy bags of salt mixtures that are to mixed
with freshwater. This type of water should stand for a few days before
introducing the organisms that you have collected. To increase the
chances of survival, a certain amount of natural sea water should
be added.
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