The tank itself weighs 600 lbs, with water, rock, equipment, etc... It will weigh closer to 2,200-2,500 lbs.
Assuming the stand sits flat on the floor and the load of the tank is distributed evenly across the base, that equates to "roughly" 180 psf. Typical residential framed flooring is designed to hold approx. 40 psf. Live load. With that said, the location in which you plan to place the tank may be able to support it depending on factors such as how close it is to an exterior wall, orientation to the joists, joist lengths, etc....
If you are unsure, then I suggest you have a licensed structural engineer take a look...
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