OTHER DISSOLVED SUBSTANCES
Sea water contains more than 60 elements, some of them in microscopic amounts:
for example, there is 1 g/m3 of gold in sea water.
All the solids dissolved in sea water serve a purpose, and that is why the salts
that are used to reconstitute water must be of excellent quality.
Some substances can accumulate in sea water and in high concentrations give rise
to concern. This is especially true in the case of organic matter, but it is possible
to eliminate them by partially changing the water or using certain devices, such
as an aerator (page 250).
As soon as the water is put in the tank, the ammonia content rises until, as
shown in the graph, it reaches its maximum level after 8 to 10 days.
Simultaneously, the bacteria wich transform this ammonia are developing and nitrites
are formed, reaching their peak around the 15th day. Other forms of bacteria also
develop, converting, in turn, these nitrites into nitrates. While the nitrites disappear
between the 20th and 25th days, the nitrates must be eliminated by partial water
The establishement of this cycle requires at least 3-4 weeks. During this period
the ammonia and nitrites reach levels that are sometimes ten times that of toxic
doses (identical to those of fresh water, see page 20).