Sea water




Which organisms?


Fresh and saltwater aquariums in education


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.

Page 1 of 4

Next page

Home    Contents    Inspiration    Facts    Collaboration   
© Aquascope 2000   Tjärnö Marine Biological Laboratory, Strömstad, Sweden
Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson