We have a 10x12 canvas top gazebo with a steel frame. My husband refuses to drill into the newly pour concrete slab. I was thinking we could anchor it down by using 35 pound concrete planters filled with play sand and river rock, and topping it with 3 inch think flagstone pieces. Maybe even put sand inside the bottom 1/3 of the hollow gazebo legs. This would probably bring the weigh to around 100 pounds per leg. Felt confident this would work. But Last night it stormed and I heard the wind ripping across the house. Maybe 30 mph winds. I fear 100 pounds per leg wouldnt be enough. Neighbor has the same one bolted down to concrete and it was fine. Cant make a mistake because if this thing breaks free it will end up in the pool tearing the new pool liner $$$$. How much weight would be enough? Other ideas on how to weigh it down?