This report is not designed to produce any conclusion in which one of the formulae examined will be recommended as a product superior to any other. All formulae have both their advantages and drawbacks, and an attempt has been made to discuss these as fully as possible. Any conclusions must always be drawn by the users ; they are the only ones who can answer the moat important question of all..."Does it do the job and do it well, or is there room for doubt?"
We have examined nine common formulae including most seawater substitutes commercially available and those most commonly produced in laboratories when the need arises. Objectivity must always be given priority in any evaluation such as this, but we had much difficulty with the problem of keeping this  document totally objective due to the nature of the subject with which we were dealing , for   example , one   could easily ignore all other factors and compare any substitute seawater with the real article - but the real thing - in this case natural seawater- itself varies. Where possible we have compared formulae to natural seawater, both in the mathematic analysis of the   major  Constituents and the final occurrence in a solution of the formula, of the minor constituents. At one stage in the production of the report the idea of comparing all formulae to a specific 'Standard Synthetic Seawater' was proposed. After consideration such a theoretical   water was produced using newly acquired analytical breakdowns of open ocean waters, and very high grade salts. This formula is given in Appendix A.

The chart overleaf gives a preliminary visual indication as to the contents of the nine formulae discussed. The expected level of any component in group A is expressed as a ratio of that component to chloride content. Bicarbonate readings are in parentheses as these are dependent on other factors and cannot be considered on their own. Bicarbonate readings   iron two of the published formulae initially appear to be extremely high until the fact that they contain no borate or H3BO3 is taken into consideration. his matter and these two special components are discussed individually a little later on. The 'expected' levels for the minor constituents could not be assessed as ratios as many naturally vary greatly. The information given in Table 3. was the parameter used. Many of these minor components showing a + symbol are still within an acceptable range for most seawaters. (Open oceanic seawaters, used here as the base, are very low in many of the so-called 'trace elements', and formulae based on figures for coastal or shallow waters could show increases.)
The iron (Fe) content of formula no.8 is problematical.   We have two versions of this formula, one of which includes a  chaelated  iron salt, the other does not.
1. KNOWLES FORMULA. Proposed by Dr.F.W.G. Knowles.
This formula is one .of the first three to be produced, and is chronologically the first of the nine under discussion.
3. LYMAN & FLEMINGS FORMULA. Proposed in 1940~after the work done by Lyman & Flaming on recalculating Dittmar's original data.
4. CHU'S FORMULA. Proposed by S.P.Chu in 1949.
6. WIEDERMANN  -KRAMER FORMULA. One of the earlier 'modern' types. This formula is commercially available, as are several slight variations using this formula as a base.
7.  J. B. CLARK'S "A" FORMULA. Proposed by Clark in 1968. A modified version of this formula was comercially available.  
8. THE SEGEDI-KELLEY MODIFICATION Of THE BACHAUS FORMULA. This is commercially available-as are a host of slight variations-and has a large number of 'trade names'. It is based on work done by both Frankfurt Zoo & Cleveland Aquarium.
9. CLARK-JENNINGS "C" FORMULA. First proposed in 1969. This is not now commercially available in the U.K.
A modification of KNOWLES FORMULA proposed by Calypso Research, to include Strontium and Bromine.

Where original dates are known they are given above.
The Knowles modification was proposed in the course of completing this work. **

Nine synthetic seawater formulae for artificial seawaters

Calypso Research Report

The examination of each formula is divided into two distinct sections.

Each formula was computed from its published form into the information shown using as a base for comparison the information given on the previous tables and the ratios of major constituents to chlorinity shown on previously. Several errors were found in published documents and these will be mentioned under each formula. Every attempt was  made to avoid mathematical errors. Most calculations were computed to seven or eight places and then 'rounded down to a convenient form. Atomic Weights used in calculations were those in use at the time the formula was originally published. Where possible all formulae have been re-calculated to 1973 IUPAC atomic weights, as have molecular weights of the salts used. (If salts are purchased now, the currently accepted molecular weight. will be given on the pack.)
The formulae as published in this report have undergone all or some of the above mathematical corrections in addition to being corrected to produce a final solution of 35 o/oo S.
All weights have been converted into grams and kilograms.
2. AN EXAMINATION OF THE SEAWATER PRODUCED BY THE FORMULA The solutions tested were treated identically. Any experimental errors should be common to all results. In the case of a known formula being commercially available a pack was purchased and the resultant solution diluted to 35 o/oo If this was not possible the formula was manufactured according to published information, to 35 o/oo S.

HomeHome Acknowledgements Contents List Preface Table 1 Major ions Introduction History Composition Basic Chemistry The Report Knowles Formulae Lyman & Fleming Wiedermann-Kramer Clark 'A' + Segedi-Kelley Clark-Jennings Properties Appendix Glossary Bibliography Conversion Factors Abridged guide Other researchers The Calypso Organization

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