I have been cleaning my gravel with a siphon and think I have been doing it incorrectly. First, my siphon fills with gravel until a few wedge into the tube slowing the flow. Then the flow is too weak to pick up any gravel. I had been just stirring up the gravel, but just seen on youtube that I should be stabbing the siphon into the gravel in which it should pick up some gravel to stir the debris out then as you lift the siphon the gravel should fall back down. What am I doing wrong with my siphon? Why does it suck up a ton of rocks and not let them down until it clogs?