There is a nice section in one of my books about DSB
's, lots of info. References to Shimek, Borneman, and others. I could scan the pages if you all desire...not sure on the legality of that though.
Here are a few points.
It says that at DSB
should be of aragonite oolitic sand, and is typically 6in or more deep. Borneman says that DSB
's alone equals or exceeds the results achieved with more traditional methods of filtration, and that it offers the basis of removing skimmers on well established aquariums. Shimek says DSB
's provide not only bio filtration but also food for many suspension feeders.
It also says that its not a simple matter of making side-by-side comparisons to measure results since the differences come from more that one variable ( as lando has brought up ).
It goes into much more detail about setup and maintenance, as well as a correct clean up crew for the sand, nutrient export, detritus accumulation, rock support, oxygen, changing sand, DSB
in refugia, etc, etc, etc.