Lol---thank you, szb. When you've been a while in the hobby and want to get The Tank of Indestructibility, suggest looking at some of the near-indestructibles: 5/8ths inch glass with corner bracing of same glued in. THe larger tanks tend to do that, or to go acrylic because of weight. My 50-gallon of that thickness weighs 80 lbs empty. My 105 gallon I'm not sure, but it took two guys and a strong woman to lift it onto the stand.
SHort of that, you CAN minimize danger simply by using that eggcrate lighting grid bottom liner. That means you never have a rockwork collapse careening into your tank glass. Put that down, put a few staggered heavy rocks down on the eggcrate that will stick up above the sand, and build your rockwork atop those spires/pilings, and it will be pretty solid. I have a palm-sized domino damsel that loves to get under the rocks and sweep all the sand out with mighty flutterings of her rather broad tail, and if I hadn't taken that precaution, I'd have reefslide-city here, but she can sweep all she likes: that rockwork stands up to her.
