I guess the fish didnt like the way I had the tank because I got home and like a pound or two of sand has been moved to form a gulley next to some boulders. Strangely the sand is all over ALL of the live rock. Like they had a freaking sand party while I was gone. The culprits are (Damsel, which already has a nest on the other side of the tank, mating clownfish, though this is a lot of sand for them to move, miniatus grouper, which has no reason to nest cause hes all alone, and lawnmower blenny, who has never showed any interest in moving sand of this scale.