When I first built my stand outside it was perfectly square and level ,..once I put it inside it sloped so bad it was scary ,..apparently the floor sloped about an inch from one end of the aquarium to the other end ,THEN it sloped about about 1/2 an inch from back to front .... needless to say there was shimming and modifications in order to get it up and level ., I guess it's all part of the game