So after thinking about how I built the desk and a solution, I pulled out a jack and jacked up the right front part of the desk up until the wood met the tank bottom. There are still minor gaps under the tank but only big enough to slip in a piece of paper in only two spots. in the corner where I was able to put two composite shims pushed in pretty far, the gap is so small I can't even slip the tip of a composite shim under the tank now. I'll remove the 2x3 brace in the front that is now too short and replace it with the proper size brace and a second 2x3 brace in the center for added security. With that done I'll still get 3/4" foamboard for under the tank. With gaps only big enough for paper I'll feel so much better about the stability of the tank. Oh, and I'm definitely going to pick up a digital level so I don't misread the bubble again.
[attachment=2]Top raised with jackIMAG0568.jpg[/attachment]
[attachment=1]New gap spaceIMAG0570.jpg[/attachment]
[attachment=0]New gap spaceIMAG0569.jpg[/attachment]