This is somewhat true, I don't disagree that live rock is a good biofilter, but sand is better period. The misconseption that live rock is the most important biofiltration was created by the people who sell live rock so they can sell more.
You would be surprized how effective a DSB can be, you don't need hundreds gallons of water flowing through your bio every second for it to work. The Nitrogen compounds disperce through the water, and therefore when there is a lower concentration in the sand due to consumption the Nitrogen flows to the area of low concentration, thats just basic chemisty/biology, high flows to low untill equal.
Infact with a proper DSB running a fork through can nuke your system as it will cause a huge dieout in the micro inverts that live in your sand, but when not disturbed will never cause a problem. The idea is to have a diverce ecosystem contained in the sand, full of pods, micro stars, worms, bacteria, snales, etc when up to a proper population these critters will maintain you DSB perfectly. Their population/movement will stir the sand so much more then you could ever hope to do (yes they are small but there is millions of them and they move allll day), allowing propper flow of nutrients in and out of the sand, wile preventing the "nuke".
I've just been busy, so i often only post when no one has posted yet lol. And mostly only when something catches my eye like someone wanting to get a monsterously large fish haha.
