That much weight (and to think I'm worried bout my little 6x2x3 LOL) honestly, something that size needs some serious, really serious, thought. The heck with the floor, I can't imagine any off-the-shelf Home Depot stuff I'd trust holding that up. I *think* I'd be looking a concrete block maybe. What kind of material are you thinking of using for a "bottom?" 10K pounds over a 128sq ft area? 4 foot tall tank calls for a minimum of 1" glass I think, and that would bow over the 8' span without LOT'S of bracing. This is a BIG tank and probably should not be put on a stand of any sort, solid concrete block would be more suitable.
Just my .02 and lord knows I've been wrong often enough before!
Later, Paul