Will's right.  Take a look at most stands available at the LFS.  From a cabinet standpoint, they're pretty low budget.  IMO, that's why they all have center posts between the doors which make it a pain to get under the stand.  If you look my stand, it has a "false" center post which opens with one of the doors and is completely out of the way.  There is a solid 3 1/2" x 1 1/2" beech beam across the center of my stand.  This should be plenty to support the center of the tank.  I guess time will tell how it holds up.  The key to a sturdy stand is to keep it from racking or twisting.  That's where it'll fail, imo.  Regular plywood will support the tank as long as you keep the frame rigid.  As far as the hood, I just wanted a hood that would stay cool and be accessable to feed or add more inhabitants.  My solution was a door that opens upwards.  Tim, I'm sure you'll do fine.

Will, the door panels are beech, but the panels in the hood are birch.  I ran out of beech, it was late Saturday and I wanted to finish it, so I looked through my stack of wood and birch was the best match .  Also, the trim pieces are all birch too (for the same reason).

Timlaw, I'm sure Jfinch would know better having done it, but as I've contemplated building a stand for my aquarium I've been looking around at prefabs at the LFS.  As far as I can see if you build a cabinet out of plywood and use some good support on the cornes and across the underside of the top where the tank will sit, you'll have a stand 10 times stronger than anything you can buy. 

Frankly I'm suprised the stands at Petsmart and Petco could even hold my weight, much less a 50-100 gallon Tank filled with water, snad and rock.  Has anybody ever experienced problems with these cheap things?

Jfinch, those birch and beech panels look fantastic.  I love the look of the 3 panels across the front of the hood rather than just one solid piece as most are.

Very nice.  I am looking for some plans.  Any chance you would be willing to share yours?  Most of the plans I have found online are over simplified.

Very nice job!!  Isn't it great to be able to put two hobbies together like jfinch has done.  I love woodworking too.

My wife would love the contrast in colors.  Perfect excuse to refinish the cabinets.