Hi Kamaaina-bob and Welcome to our little community (not so little anymore!) :-)
It is getting ever more popular here in Europe to have
DSBs and mud-based
refugiums; however, I know very very few that run their systems entirely as EcoSystems. One of my friends in Germany actually has successfully run his tank for almost three years on pure natural filtration. He doesn't have a
skimmer, but has a sand bed, although I wouldn't call it a
DSB, as I don't think that it's deeper than 4". He has no
cyano problems, his corals have great coloration and grow steadily. I have to preface this statement though by stating that he
does have a lower bio-load than most of us have.
I think the German reefkeepers are maybe thinking about more along these lines, but I haven't heard many people talking this way here in Sweden. I'm meeting up with some semi-local reefers though in two weeks and I'll talk with them about it.
