Last month I built a patio with a pergola above it. The 6"x6" posts are sitting on a concrete footer 36" below the patio. The seat walls are also on a concrete footer so I filled the holes with stone up to the seat wall footer, then I have 5" of concrete under the columns and wall. My question is what are you guys doing with the void around the posts inside the columns? Do you leave the void or fill it with sand? If I push the posts hard they barely move but do have some give.