Here's another question - if the sand shifting/sifting fish like gobies require well established sand beds with lots of pods etc., what do you do in the meantime? I have a 2" SB in my 29g with a bunch of hermits and snails and now a pair of clowns that seem to be digging a ditch in one corner every night. The tank is 6 weeks old with lots of live rock and I know I already have some pods. Would a goby be OK already? If the sand needs to get established, won't a bunch of bad stuff build up and then get released when I introduce a sand sifter?? How do I know if my flow across thesand is adequate? SHould I see it moving?? thanks!