These blocks & what comes w/ the Ecomagic filter (Bailey Brothers show
Eco Magic Filtration System) are supposed to provide the correct porosity and at an adequate depth from the surfaces of the stones so that bacteria can get in there and live in nearly anoxic conditions. Under these conditions, they can break NO3 down, producing N2 and either oxygen or other oxygenated byproducts (not sure). This is pretty much the same as having liverock in a marine aquarium (except the bacteria species may be different - again, not certain).
In the case of the ecomagic filter, I suspect that the filter's supplied rock in not adequate to house enough bacteria to do NO3 conversion for a (for example) 55g tank. By specifying that their UG plates be mounted under a couple of inches of substrate (gravel), and running it as a low flow RUG, I think that they are counting on these NO3 digesting bacteria to colonize the tank bottom as well.
In theory, it looks pretty good. Having seen the Ecomagic web site, I can say that I have some unanswered questions...
I think the main thing is to try to establish whether or not the special rock media is actually allowing NO3 eating bacteria to survive and multiply, or if it merely acting in the same capacity as zeolite.
PS - nice to know someone here who has called in, Draal5 - I like the show despite the perpetual interruptions of the one brother over the other, and the inordinate praise of biowheels, but hey, they've got sponsors to consider.