Vertically, the metal stand legs should hold the weight of the tank, rock and water.
My first concern is how much weight the floor will hold. If the floor is concrete, there is no issue. If it is wood, there may be an issue as all the weight is concentrated in 4 small locations.
Weight issue aside, my next concern would be horizontal stability (think bumping into the end of the tank). There does not seem to be any diagonal bracing to keep the stand from moving side to side. This would probably be my greatest concern - the tank shifting sideways and falling over.
My first concern is how much weight the floor will hold. If the floor is concrete, there is no issue. If it is wood, there may be an issue as all the weight is concentrated in 4 small locations.
Weight issue aside, my next concern would be horizontal stability (think bumping into the end of the tank). There does not seem to be any diagonal bracing to keep the stand from moving side to side. This would probably be my greatest concern - the tank shifting sideways and falling over.