Hi all. Built a custom acrylic frag tank and hadn't really thought about it until someone suggested to me locally that I put foam under the tank. We really like the wood. It has been sitting full for months just fine as we leak tested it and both got really busy with work. We are not putting rock or sand in there - if we do it will be rubble. It will only have frag racks. If the stand is flat and level is it necessary?