I've never tried to ranch copepods up as food, nor marine copepods, but most of my career when I was a biologist involved working with them in mixed small-pond or puddle communities and I've certainly grown a gazillion of them over the years.
So, to the extent that culture methods transfer from fresh to salt water, I'd suggest trying to grow them in a somewhat mixed culture (at least in fw, and I believe it's true in salt too, the young stages are all carnivorous even in species with herbivorous adults). The 'cleaner' and more single-species you try to keep a fw copepod culture, the less well the culture does.
On occasions when I needed a bunch, I usually figured my best bet was to set up a number of cultures and figure that only the ones that got off and running the best would I carry onward.
Dunno about temperature/light etc, I expect they're a whole lot different for marine vs the copepods I've known, hopefully someone else can help there.
Good luck,
Pat
