Hello all. I just bought a 55 gallon tank to upgrade from my 20 long. I'm planning my scape and I want to create a large hill or slope on the left side at least 6 inches high. I don't wan't to just pile tons of sand to that height as that could cause some problems down the road. I'm thinking of taking some mesh bags, filling them with large grain gravel or even lava rocks. Stack them to my desired height creating a rough "slope" shape then filling in with sand on top. Do you think this will work? Or have any better suggestions for creating a tall hill?