The way I understand it, and a couple of theory I have.......
The main theory and why the DSB system works is that it uses anerobic (without oxygen) bacteria to decompose the organic material (detitrus). By forcing water or air up or out would negate this anerobic enviroment......
Just where it becomes anerobic (how deep) has been under debate, some say as little as 5mm if I remember right.
A DSB creates a "nitrate factory" where nutrients are slowly "eaten" and processed. This is a slow yet constant process that as they DSB matures become more productive. Thus because of this slow constant process there is alway "x" amount of nutrients in the water. As we know nutrients contribute to coloration and growth, and SPS are extremly finicky about this level. The nitrates are controlled by water changes.
Conversly on the other side of the spectrum, and how I have come to think of it as, the Barebottom method takes out that "x" amount of nutrients out of the equation which creates a void where the only nutrients that are hopefully present are filtered out by overskimming and filtersocks before it has a chance to break down and be taken in by the system. The benifit of this is "void" can be filled again by feeding more and dose more phyto so those "x" level of nutients are used in growth producing materials....nitrates in theory will not exist. In short is 100% is your total nutrients and your feedings and in water nutrients are 70% and the DSB is 30%.....by removing the DSB, 100% of your total disolved nutrients is going to feeding, hence growth....and you can adjust that level if needed if browing occurs.
But it has been debated that a small remote sand bed adds stability to the system of a BB tank and allows "some" contant nutrients to remain in the system rather than some, none, some, none pendullum. I found this to be true when switching to BB and have added a SMALL SSB to combat this.....with excellent results.....my colors stabilized and are great all around.
The other option is the SSB, which is the option I prefer. Has the looks of the sand bed if you don't like the BB look, and if the 5mm is correct has the possibility of creating an anerobic zone without the deep reserves of much that be lost inches down resembling oil/gas reserves in a couple of years.
But the main problems that you asked about with the DSB is clumping due to calcification of the sand bed which happens from following the rule of never stirring you sand bed or having gobies or cucs as the DSB rule book states. I don't agreee with that though, I say stir it up and constantly release those materials rather than waiting for a rock rescape or a tank move to upset a "pocket" and cause a tank crash........ask builderguy about that one........ this accumulation of materials that after time is what people call a "ticking time bomb" as some say, and I agree with.
However, nothing is for certain, and people have been going between the three types for years.........
I think a DSB is more suited for a Softie and LPS tank because they do better and thrive in nutrient rich enviroments, and BB if not SSB for SPS tanks......for mixed I say SSB.......which is yours tank?
, I think MAx told me it had several hundred pounds of sand (500# comes to mind for some reason now).
