Then comes the pouring of ADA Amazonia(normal type) into the tank with more on the back of the tank and less on the front forming a slope. 1 big pack was really more than enough for a 3x1x2 tank. This step is better to have a small cut on the bag or using a cup to scoop so you will not accidently "over pour" the sand causing it to disturb the already nicely form substrate system done previously.