Check the same reference I included in your other question: ;)

http://www.haloarchaea.com/resources/halohandbook/

Marine aquarium artificial seawater salts are very good these days and save a lot of hassle.  For halophilic bacteria use ordinary seawater or a synthetic seawater mix made up to seawater salinity and then add NaCl to increase the salinity to the desired level.  Dunaliella and hypersaline PS bacteria grow quite well and they do not seem to notice that although the Na & Cl in the water is higher than seawater the other ions have remained the same as seawater. Seawater + NaCl autoclaves well.

If you try and make up a complete hypersaline solution you find that it will not dissolve or largely precipitates if you try and autoclave it. Similarly if you make up an artificial seawater very close to real seawater you may find that it will not autoclave well and algae will not grow in it because there is no available phosphate.

One thing to be wary about most artificial seawaters: they usually have a quite different Mg & Ca content to real seawater. For most organisms that does not matter much but the balance of Mg & Ca is critical for calcifying organisms such as corals and calcifying algae such as Halimeda. They may grow but not calcify properly. One trick is to add a little bit of Strontium chloride. The equilibrium constant for SrCO3 is much more favourable than CaCO3 and so it acts to nucleate CaCO3. That is why you see it sold in aquarium shops (took me a while to work out why they sold it).

Try marine broth (Difco 2216), for detailed recipe see the link https://www.bd.com/europe/regulatory/Assets/IFU/Difco_BBL/214907.pdf

Follow the ASTM 1141-98 standards for preparation of artificial seawater with 10 chemicals mixing in distilled water.