I have a 135gal tank. It has a foot print of 72x18. Its not level. The water level is slightly forward and to the right.(water level is higher on the right side than on the left) Its on a DIY stand that is level, but the floor is concret with a thick carpet which isnt level. The stand is a frame of 2x4s and wrapped in plywood around the sides and top. the bottom is just 2x4s.... can i shim this some how?