I used to move 90 gal AGA and Perfecto tanks by standing them on end, squatting down and leaning my shoulder into the bottom glass just below the midpoint. Grab the top of the tank, and rock it back onto your shoulders and stand up in one motion. I'm 5'11" and at the time I wieghed about 165 so it's not really a matter of brute force so much as technique. Now Oceanic 90's were another matter altogether, at least for me. But if you really want to move a tank by yourself use a refrigerator dolly. I moved a 210 up two flights of steps with one by myself about a year ago, and I'm an old man!