How much lean b4 you shim up the stand?

[Delphinus]

You say the sides of the tank were perfectly vertical before you shimmed?

Are you sure the wall is level (100% vertical)?

What I'd do, if it was me, is measure the level of the tank horizontally in both axes, and then shim based on that. Now, if it was my tank, and I did that... and the distance to the wall wasn't the same at the top and bottom, then I'd assume the wall is out, and leave the tank alone.

(If, however, I then found that the sides weren't vertical anymore, after verifying the tank is level horizontally, then I'm not sure what I'd do. Contact the manufacturer, I guess. I don't make tanks for a living so I can't claim to have a deep understanding of the processes involved, but it seems to me that there's no reason for the tank not to be perfectly square when empty. I think it would mean the edges weren't squared or that the glass isn't sitting squarely against each other.)