I've seen a few posts on various FB sites about growing your own greenweed, both string and cabbage, most seem to be in an old fish tank in part morning sun.
Fed with aquarium plant food, I think . . . Some use aerators, some don't.
I'll check for a post this arvo and provide an update, as I have no access to FB at work.
Oh and apparently top up with rain water, or aged tap water, when water level drops due to evaporation, otherwise it becomes to salty.