In the past I found that a 4" sandbed with adequate critters would drastically increase the bioload that a tank could sustain with pristine water conditions. My dsb tanks had such abundant fauna that they actually required mandarins to keep the pod population in check. That being said Im considering going a little shallower with the sand for my next tank. My question is: has anyone experimented with keeping different sized layers of sand? Im thinking of stratifying the sandbed with a quarter inch layer of 6mm cc at the bottom, half an inch of 2-4mm and then an inch of oolite and the top layer 1-2mm fiji. For some reason this seems like a good idea but I have nothing to back it up with.