Hello, I am considering experimenting with a FW DSB. My tank is on order: http://www.fishtanksdirect.com/red-sea-reefer-170-black-34-gallon-glass-aquarium-set-r42111.aspx It will be a high tech set up with pressurized Co2 and LED lighting. I am planning on using the sump as a refugium on an opposite lighting schedule as the main display. Plants will be high light demanding, delicate species. Inhabitants will include Crystal Red Shrimp and peaceful shoals of compatible fish/Snails. I have the 8 liters of SL aqua soil, which I was going to place on top of 30/60 mesh Black Diamond Blasting Grit (also black in color), which I was planning on placing on top of a sprinkling of Osmocote Plus and some mulm from one of my co-workers' well-established, healthy molly tanks. This is the article I am basing my decision on to try a FW DSB: http://www.wetwebmedia.com/ca/volume_7/volume_7_1/dsb.html. The thing which prompted me to research the DSB is seeing a 3-year old setup in person while visiting my sister in CA. It was stable, and without algae problems. It had metal halide lighting, pressurized Co2, and a canister filter. The plants were challenging species; I had never seen them in person before because my town is in the grips of the low-tech set-up. The thing that attracts me most about the DSB is the biological filtering large-scale capacity. Plus, I'm somewhat of an experimenter. One concern which has been brought to my attention is the lack of nutrients in the blasting grit. Also, the possible impaction of said grit. My thoughts on these issues are: The Osmocote Plus does provide nourishment to plant roots; I used it in my old low tech set up, and the Anubius, crypts, and swords thrived on it. However, since particle size is important in the DSB, what if I manage to crush the Aquasoil fine enough to suffice? In the powder size which I ordered, it looks to be about 2-3x too large as it comes. It will be nutrient rich for the plant roots, and provide the different levels of oxygen zones required by the nitrifying bacteria along with the surface area required for the large amount of biological filtration I desire. The compaction issue is avoided by keeping enough live Blackworms and Malaysian Trumet Snails. I plan on using my sump refugium as a safe breeding zone for the blackworms so that I can continuously restock their population in the main display. At any rate, the depth of the sand bed is not something I am set on; I am open to foregoing a DSB if the possible consequences outweigh the benefits. But I am just hoping anyone on this forum might have some thoughts they'd like to share about the DSB?