Well, I'm really freaking anal about removing crud from my BB tank because that's the whole idea about going BB. Without the critters and extra bacteria that lives in the sandbed, accumulating crud is a recipe for all kinds of nuisance algae problems somewhere down the road. If our hands weren't so wet during WCs in our three tanks, I'd take pics of the crud we siphon out as well as the crud that accumulates in our mechanical filters. It ain't pretty
