In article ,
says...
I'm running a microreef (15 gal) with no sand and a bunch of live rock
(tank is about 1/2 full of live rock). Nitrates are zero, but I have to
watch the pH.

I used to have a 65 gal tank with a 3-4 inches of live sand. When I
moved out and broke down the tank, the sand was all poopy underneath. I
had a whole bunch of red and blue legged hermit crabs which I thought
would sift the sand. Apparently they didn't sift the sand much below
the depth of 1/2 inch. Lots of cool humongous worms in the bottom of
the sand though.

Are people concerned about all the poopy stuff that builds up down in
the sand?

Actually, that "poopy" stuff is nitrifying bacteria, and is the goodness
of a DSB. :-) The crabs aren't supposed to sift much below the 1/2 inch
mark... I guess -- I don't really know how far they're "supposed" to
sift, but definitely not the whole depth of the DSB -- only the top
layer...

--
7y FW -- 33g & 55g
100 gallon reef-ready air tank. (Converting to reef)