I've used 2 different volume calculators and both have it at 260g, a 6x2.5x2 would be 225g, this is 7x2.5x2. I'll look into yacht varnish or something similar to waterproof it. Stock will be spotted gar, bichirs, tinfoil barbs and a lima shovelnose so far. Put another 1" board of ply on top and got my foam on top of that, ready for the tank to be filled on Thursday!