Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I do the same double shim technique, but without the tank on the stand. Then I can lift the stand, and keep on re-setting the shims until it is right. (and there is ALWAYS a shim or two lost under the stand)
Most of my stands (well, all of them now) are on firm flooring, not carpet, so whatever the level shows the stand is doing it will not get compromised when I add the tank.
If you are trying to make this work over carpet you may have to do your best on the stand, then fill the tank and check again. Carpet or pad may squish flatter in some areas than others when the weight of the tank is added.
Yes, the composite shims are a bit harder to cut, but the knife or hacksaw does a pretty good job of scoring them, and they are already grooved, too.