I just paid 10 bucks for 50 pounds of pool filter sand. It's my understanding that most sands are too fine. They tend to pack down and block the flow of water beneath the surface of the sand thereby creating "dead" zones within the tank. The PFS has a diamater of between .45 mm and .55 mm which should be perfect for a bottom. Idealy, you'd first lay down a 1 inch layer of soil and cover it with sand to provide a better environment for the root growth of your plants. Bill in Va.