Reefwick,
Dont use "adjustable" feet to help with leveling your tank/stand. Reason being, this displaces a LOT of weight right on the "feet" themselves and could weaken the structural integrity of your stand.
What i use to level my tank/stand is a deck of plastic cards. I cut them to the width of the bottom of the stand that sits directly onto the floor and use these pieces as shims, 1rst shimming under the 4 corners of the stand.
Once the tank/stand is level, place more shims in between the 4 starting shim locations to help even out the displacement of weight. Keep shimming until the shims feel the same in "tightness" of fit. Also test for looseness of other shims for "over-shimming".
Also... your tank should be at least 1/2 way full of water prior to leveling it. I usually fill my tank 3/4 full with water, then wait 12-24 hours for the stand to shift and settle before shimming.