[Anemone]

As everyone else has said, with that size tank, as long as the stand top is flat, you won't have a problem. The stress on the tank seams becomes an issue when the tank bottom is not evenly supported.

So, it's the aesthetic of the differing water level vs the aesthetic of "something" added to the stand. As Mcgyver said, wood blocks (or rounds, depending upon the shape of the stand's legs) that are stained the same color as the stand, or those screw-in table-leg levelers would so the trick without being too distracting to overall look.

Kevin