Step 2: Siphon Out That Old Water!
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)