I am not sure i have the highest quality level tool and am not sure just how perfect the surface should be. The bubble in my level is in between the two lines however closer to the line in some spots further over to the next line in other spots -still in between the lines at all spots. Is that close enough? Plus I have a 1/2inch Styrofoam pad under the tank will this compensate and protect against any minor contortions and leveling issues? Thanks!