I dont know if it helps, but on my little 12g tank I like to stir up the water as much as possible to get any dertitus off the rocks and stuff so it's floating in the water. That way when I start siphoning it out I get more nasty stuff out with the water. I dont think it really matters much on how you do you though, but I stir up all the junk every few days like that to let me filter get it all and it seems to keep the tank sparkly clean.