You need to level it. The bottom panel could crack if you don't. If it is very unlevel, cut a small square of 2x4 and put it under the tank. A 2x4 is actually just 1.5 inches thick. If that is too thick, use shims. If that is not thick enough, add shims on top of that. That is just if it is VERY unlevel. Otherwise use shims. I have used composite shims to level a double 40 stand.
