How far "out" is Too far out?

[Keri]

So here's the story....


We're trying to find a spot in the basement for our 120g tank (with 33g sump)
The BEST spot (for plug ins, looks, most space) is leaving us either 1/4 or 1/2" unlevel from one side to the other.

It's definately the tile floor, not the tank or stand that is out. Is even 1/4" too much? I REALLY don't want this thing blowing out on us 6 months down the road.

The only other place we could put it would be within a couple of feet of the fireplace which I'm not comfortable with either.

Does anyone have any suggestions on leveling things out? I want to put a shim in or soomething but does that then leave parts of the stand not in contact with the floor? I need ideas!

Thanks!!!
Ps: the tank is the standard 2x4x2, the stand is slightly wider and longer.