I bought a prostar 200 and there is a gap between the top of the stand and bottom of the tank in certain areas. The gap is big enough to allow a piece of paper in between. The tank is not a true rimless aquarium as there is a bottom rim to the tank. I filled the tank up and leveled it on all four sides and it’s dead center. Some people have told me to put a leveling mat under the tank but I don’t see how this would make a difference since if the gap is causing a pressure point the mat wouldn’t offer any support. Any help would be appreciated.