Seawater is a complex solution containing a wide variety of organic and inorganic chemicals. While some of these are frequently discussed by reef aquarists, others are rarely mentioned. Without a working knowledge of what is present in natural seawater, it is often difficult to assess aquarium problems, as well as the claims of manufacturers and other aquarists about what additives and methodologies are desirable in maintaining reef aquaria.
This article is intended to help aquarists better understand the water in their aquaria. It strives to give a better understanding of what happens in seawater than does a simple table of elemental concentrations, although such tables are also provided.
The topics covered are:
The Water Itself
Seawater's Physical Properties
pH
Elements in Seawater
The Big Four Ions
The Other Major Ions
Minor Ions
Dissolved Atmospheric Gases
Trace Elements
Complexities to Minor and Trace Elements
Organics
How do Ions Behave in Seawater?
How Ions Behave in Seawater: Simple Ions
How Ions Behave in Seawater: Carbonate and Bicarbonate
How Ions Behave in Seawater: Calcium, Magnesium and Strontium
How Ions Behave in Seawater: Sulfate
How Ions Behave in Seawater: Phosphate
How Ions Behave in Seawater: Metals
Nitrogen Compounds in Seawater
Iodine in Seawater
An Artificial Seawater Recipe
Conclusion
References
In the references section are links to articles about many of the individual ions present in seawater that most interest reef aquarists. This article does not try to describe what commercial artificial seawater and reef aquarium water contain. The following linked articles are more useful for those purposes:
A Chemical Analysis of Select Trace Elements in Synthetic Sea Salts and Natural Seawater
It's (In) the Water
What We Put in the Water
It Is Still in the Water
The Composition Of Several Synthetic Seawater Mixes
Link to original article:
What is Saltwater? by Randy Holmes-Farley