This is the fun part! For this step i would get the bucket and the siphon tube...and some towels if you don't have good aim! (if your a guy you can easily test this out...hee...hee) Its sorta hard to get the siphon started. What i do is get the end of the tube (small end!) and put it right above the bucket. (that you have right in front of the tank) Then put the big end so that the whole "big end plastic part" is submerged. Then (wait for it) suck on the small end until it starts the siphon. WATCH THE TUBE SO THAT YOU CAN TAKE THE TUBE OUT OF YOUR MOUTH AND PUT IT INTO THE BUCKET BEFORE YOU GET A MOUTH FULL OF FISH WATER!!!! This method is the easiest, quickest, and probably most reliable out of the "Shake method" or the "Blow Method"
Once you have a constant flow of water going from the tank into the bucket you're going to want to shove the Big end into the gravel, or to use the proper lingo, the "substrate." then pull it out and let all the gravel fall out of the tube. Then move to a different section. Keep moving around until you have either sucked on all of the gravel or sucked out 30% of the water. In the picture i have sucked out around that 30%. DO NOT GO OVER THIS AMOUNT! if you do you will risk stressing out your fish. if you're doing it right you will see dirty nasty water going up the tube and into the bucket! (duhh)