The Constituents Of Seawater

The seas and oceans cover the majority of the planet surface. Within those seas the wild reefs have grown and all of their needs are met, be that calcium or whatever. The life on the wild reef has had a very long time to adapt to the sea, which is considered to be stable.

Some of these life forms end up in the home marine aquarium. With the natural seas being so stable it follows that for success the conditions on the wild reef should be duplicated as near as possible, and conditions provided that successfully permit life to function and be healthy.

Seawater quality is the number one on the list of ‘must haves’ for success so it follows that the seawater used should be as close as possible in make-up to the natural kind. In much earlier days aquarists would obtain some constituents – not all of them by any means – from a chemist and mix up a brew. Livestock existed in this fairly well for a while but trouble usually appeared. Nowadays there are many high quality dry salt mixes available which the manufacturers state equals the natural type. Be that as it may, the appearance of these dry salt mixes has brought the successful maintenance of a marine system within the reach of every aspiring aquarist provided the interest in the hobby is maintained and the requisite maintenance is done.

Seawater is a mix of many things, some of them present in major amounts, others in trace amounts, and more with a very tiny presence. So for the benefit of anyone interested there follows a list of the make-up of seawater. There is clearly no requirement of any kind for an aquarist to know them but as said it may be of interest. It could also be of use for aquarists who wish to maintain natural levels of important parts such as calcium etc.

Major Elements. (All measurements in mg/l)

Chlorine

18880

Sodium

10770

Magnesium

1290

Sulphur

884

Calcium

412.1

Potassium

399

Bromine

67.3

Carbon

28

Nitrogen

15

Strontium

7.9

Boron

4.5

Silicon

2

Fluorine

1.3

Trace Elements. (All measurements in ug/l)

Lithium

180

Rubidium

120

Iodine

60

Phosphorus

60

Molybdenum

10

Zinc

4.9

Argon

4.3

Arsenic

3.7

Uranium

3.2

Vanadium

2.5

Aluminium

2

Barium

2

Iron

2

Nickel

1.7

Titanium

1

Copper

0.5

Cesium

0.4

Chromium

0.3

Antimony

0.24

Manganese

0.2

Krypton

0.2

Selenium

0.2

Neon

0.12

Cadmium

0.1

Wolfram

0.1

Cobalt

0.05

Germanium

0.05

Xenon

0.05

Silver

0.04

Gallium

0.03

Lead

0.03

Zirconium

0.03

Bismuth

0.02

Mercury

0.02

Niobium

0.01

Thallium

0.01

Thorium

0.01

Tin

0.01

Hafnium

0.007

Helium

0.0068

Beryllium

0.0056

Gold

0.004

Rhenium

0.004

Lanthanum

0.003

Neodymium

0.003

Tantalum

0.003

Yttrium

0.0013

Cerium

0.001

Dysprosium

0.0009

Erbium

0.0008

Ytterbium

0.0008

Gadolinium

0.0007

Praseodymium

0.0006

Scandium

0.0006

Holmium

0.0002

Lutetium

0.0002

Thorium

0.0002

Indium

0.0001

Terbium

0.0001

Samarium

0.00005

Europium

0.00001

Radium

0. 00000007

Protactinium

0. 00000005

Radon

0. 000000000006

Constituents with a tiny presence.

Technetium

Ruthenium

Rhodium

Palladium

Osmium

Iridium

Platinum

Astatine

Francium

Actinium

(Reference: ‘Baensch Marine Atlas’. Helmut Debelius & Hans A. Baensch)


The Constituents Of Seawater
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3 Comments
  1. Sea water is certainly a more than just h20! It certainly underlines the need to be vigilant in your water testing. Saltwater master test kits usually contain tests for ammonia, nitrite, nitrate, pH and sometimes alkalinity. It is also good to have a Hydrometer handy to check your salt levels

  2. Certainly is! It’s the number one ‘high quality’ requirement, closely followed – in a reef system anyway – by lighting.

    Johns last blog post..Is It Confusion That Prevents People From Starting Or Something Else?

  3. Although the vast majority of seawater has a salinity of between 3.1% and 3.8%, seawater is not uniformly saline throughout the world. Where mixing occurs with fresh water runoff from river mouths or near melting glaciers, seawater can be substantially less saline. The most saline open sea is the Red Sea, where high rates of evaporation, low precipitation and river inflow, and confined circulation result in unusually salty water. The salinity in isolated bodies of water (for example, the Dead Sea) can be considerably greater still.

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