Welcome to the board!
In your tank, 40lbs will only give you a little over 1" of sand. For a deep sand bed, (dsb) which will help alot in the denitrification process, you need about 3-4" inches. Go to your local fish store (lfs) and ask them for some aragonite sand...about half the price of live sand, and it will become "live" in a few months as well.
Have fun and keep asking questions!