Siphon Technique

I have had my tank going for a year and I dont think I am siphoning correctly. I recently bought the Aqueon 25' siphon thing that you hook to the sink to create the siphon. Its much easier than siphoning into a garbage can. I know the siphon is strong because I actually siphoned out too much water last night without knowing it. But while I was siphoning the sand I noticed that the detritius was moving around in the siphon tube but then falling out the bottom and back into the sand. When I siphon I put the tip into the sand bed and let the sand tumble around. I thought this would allow the detritius to be sucked out when it became separated from the sand. Some of the detritius may be sucked out but not all of it.



So am I doing something wrong or is the diameter of the siphon tube not big enough (it does suck sand up through the tube).