IMHO putting it on the ground would not look good unless it was a floor to ceiling tank because it would be difficult ot look at it unless you were sitting on the floor which i think would get really annoying after a while, my tank is currently up to my chest and it bothers me that i have to sit on a chair to watch my fish and i couldnt imagine needing to sit on the ground and depending on size, moving it later to a stand may be troublesom. oh and as long as the floor is level there is no harm, but if the floor gets paricularily cold the heater will constantly be on