You only want foam under rimless glass tanks that rest on the bottom (sides on top of the bottom panel) and acrylic tanks. It smooths out and tiny bumps and imperfections in the wood. With a rimmed tank this isn't needed, the rim supports the full weight and wont cause the glass to crack due to some sand or a bump in the wood.
As for it being unlevel, it is possible that even though the stand top and floor were both level, together they were a bit off. 1/8" really isn't much so it wouldn't take much to reach that point. The foam may have caused it, but it may also not have.
How did you shim the tank? Did you do so under the low side of the stand? You always want to shim under the stand, not under the tank. If I were you I would pull the foam, see how the tank is sitting. If it is still a bit low use some shims under the low side, it really shouldn't take many with the length of the tank.
I do feel your pain trying to level it. I recently moved to a new place with very unlevel floors. Its and older house so the floor droops in about every direction possible. I have more shims touching the ground than stand at this point.
As for it being unlevel, it is possible that even though the stand top and floor were both level, together they were a bit off. 1/8" really isn't much so it wouldn't take much to reach that point. The foam may have caused it, but it may also not have.
How did you shim the tank? Did you do so under the low side of the stand? You always want to shim under the stand, not under the tank. If I were you I would pull the foam, see how the tank is sitting. If it is still a bit low use some shims under the low side, it really shouldn't take many with the length of the tank.
I do feel your pain trying to level it. I recently moved to a new place with very unlevel floors. Its and older house so the floor droops in about every direction possible. I have more shims touching the ground than stand at this point.