Looks good so far man. Make sure to put at least 2 inches of cap over that soil, you'll need it. If it's at all possible, you'll be better off in the long run mixing the soil and crushed coral together rather than layering them. The calcite will help to buffer the pH a little bit and keep the bacteria happier, but the most important benefit is reducing the bulk density of the soil. That allows better root penetration and reduces highly anaerobic spots.