Does anyone know how important it is for a glass 29 gal to be absolutely level both ways? We just filled one that is level across the front, but there is a difference of almost 1/4" when viewed from the side (front to back). We would have to empty the tank again and shim the back edge of the stand. It is on carpet and there may be some variation in the wear of of the carpet or pad that close to the wall; it could settle down with time? Want to get it right before we add fish. Thank you.