I have used crushed coral together with sand. In case your about to use sand get plenty of snails to keep it clear, you don't need being vacuuming it or stirring it up,it make a mess!! beams: The beams act to assist the ground joists. These beams could be manufactured https://aquarium-setup-tips65061.blog-eye.com/37615850/indicators-on-aquarium-setup-tips-you-should-know