they can be very useful no doubt, i woudl agree, but in some cases hes out to lunch, in this case i'd take it like a grain of sand. i mean how can "air" flow under the rocks when its in water. rock is porous for a reason, it allows for the life to live and also allows the water to flow through it, so it is passign the bacteria that breaks down the organics. also the more rock the faster the organics get broken down and the more places for fish to hide and for corals to be placed.
with his DSB
he really should have to worry about how much nitrate is produced because the DSB
if done right (with rock burried in the sand) the organics as they are beign broken down into ammonia nitrites then nitrates as it passes through the rock and to the DSB
, those critters that live deep in the bed where there is no oxygen, will break down the nitrates and creat little nitrogeon and oxygen bubbles in the sand, which will then be released by the critters that live in the top inch or so of sand.
as well his chaeto will use the nitrates and organics to grow and in turn filter more water.
if all is done right a skimmer will just help keep the water spotless but not totally needed.
steelo in his later videos also says he plans only on doing waterchanged ever few months which is totally stupid, sure it saves money on salt and water but in the long run dosing the system and possibly needign a calcium reactor is far more expensive then a bi weekly waterchance with quality reef crystals