Marine fish and invertebrates are very sensitive animals, requiring the utmost care and attention to water quality, lighting and filtration.
  Most fish are easier to keep than invertebrates and will tolerate any degree of variance where water quality is concerned, this is, of course, not a trend to be encouraged and the marinist will find that by improving water parameters fish remain healthier, display better coloration and live longer.
  The only satisfactory way of confirming the presence of various dilute toxic substances is to use an accurate test kit.
  There are six of these kits which all marinist should own and use: ammonia, nitrate, nitrite, pH, specific gravity and copper. Ammonia and nitrite will enable the maturation of the aquarium filters to be monitored and confirm hen it is complete. The test will look for overstocking, overfeeding, mortality and a breakdown of biological filtration.
  Specific gravity and pH are very useful in enabling the stability of the water to be managed, as the parameters are easily adjustable. The nitrate kit will have no initial use, but it will provide a vital aid in assessing the quality of the mains water.
  There are many other test kits available to mark the progress of an aquarium and confirm there are no impending disasters: dissolved oxygen, carbon dioxide, alkalinity, phosphate, silicate, calcium, redo potential, conductivity, iron, ozone. Tests carried out by electronic meters are highly accurate, but their price might deter hobbyists.

WHEN TO TEST

Monitoring a new set up will involve a nitrite and ammonia test to be carried out each day. pH can be measured every few days at the beginning and more often as livestock are introduced. Once the tank has matured, ammonia and nitrite tests can be reduced to weekly for the first few months but every day before new livestock is introduced.