Ya you can use the same basic design for any size tank. I added the middle support cause a 75 Gal tank is close to 1000Lbs when it is full with everything. You can redesign the stand how you want it to fit what ever size tank you need. I would say if the tank is over 3 ft them add the center supports. Under you can get away with out them. For smaller tanks you can use 2X4's. I liked the way the the 2X6's looked and the extra strenght was a plus too. I had some left over from building a bed for my brother. Here is a link with All-Glass tank dimensions
All-Glass Aquarium - 20" New Economy Full Hood Most tanks by any manufactuer (sp?) will be close to the same size. If you have any questions let me know.
MAHA