Am also working in Actinomycetes.. Here am providing the answer for your question...
Ans: Starch casein agar supplemented with seawater and also Supplemented with Actidione 20 mg/l and Nalidixic acid 100 mg/l were added to minimize the other fungal and bacterial growth respectively, was used for the isolation of actinomycetes or streptomyces in situ. The samples were appropriately diluted with sterilized seawater and 0.1 mL was spread on the media.
What range of halophilic? If medium halophile, just use seawater, if hope to isolate extreme halophile add appropriate amount of NaCl or seasalt in the media. Enrichment is better for isolation but hope to isolate diverse streptomycetes, pre-treat and direct spreading on media is better.