i'm new, so i could very well be wrong, but this is what i *think* i understand from my reading: i should run a "backwash" cycle until the water in the viewing-tube thing is clear, which "un-compacts" the sand and washes it out. then run a "rinse" cycle, which re-compacts and re-levels the sand, making it a nice strong filter media again. did i understand this concept correctly? tia!