My 6 year old twin boys wanted a pet. As a reward for showing us their responsibility, I set up my old 10 gallon tank in their bedroom. This just made me want to get my tanks going again. I've had them down for about 7 years now, ever since we moved. All my stuff has been stored in the garage. Needless to say the old aquarium stand was used to store things and wasn't in very good shape. Additionally, I wanted to set up both my 55 and 29 gallon aquariums and the old stand was too short for the 29 to go underneath. So, to get going in the fish hobby again, I turned to one of my other hobbies, woodworking. I designed this stand that sits a bit higher. The bottom of the tank is 33" off the floor and the top of the tank is at 53 1/2". At this height, you don't have to stoop so low to gaze in the tank.
The 55 gallon tank will end up being a Malawi Cichlid tank. The 29 gallon tank will be a breeding/fry growout tank. Here's the fish I've selected for this tank. I haven't purchased them yet, so there may still be some changes. I already swapped out the auratus and demasoni.
Motivation for building the new stand was fish and the lack of a suitable place to put the aquariums.
Old Stand (picture coming)
1 sheet 4x8 3/4" Oak Plywood
1 box 2-1/2" galvanized screws
4 8' pressure treated 2x4 (I didn't have to use pressure treated, I just had
plenty on hand)
1 pint Pecan stain
1 pint gloss polyurethane
Sand paper, 100grit, 220grit, 600grit
Paint Brush (optional, only used with poly)
Rag (for stain)
2 8' 1-1/8" corner molding
1 8' base board molding
Wood Glue
The frame is constructed of sister'd 2x4's. There are 2 separate square frames, one front, and one rear. I sister'd the boards together first before making the squares. Since the inside piece is offset from the outside piece, this helped me ensure it was square when the pieces were attached to one another to make the square. After completing both the front and rear frame supports, I attached them at each end and in the middle, both top and bottom. There is no bracing for lateral movement in the frame itself, that is accomplished with the plywood sheathing applied later. Unfortunately I failed to take any photos of the frame before I sheathed it, but I did attempt to get some pictures of the frame underneath the sheathing.
The weight of the aquarium rests only on the edges of the aquarium, so I wanted to ensure that the edges were the strongest part. Therefore, the outside of each side of the frame contains a single member that spans the entire length. The inside member of each frame is offset to help keep the whole thing square.
It took me about an hour or two to cut the pieces. Then another couple of hours to assemble the frame.
In the picture below you will see where the plans above deviate from the
actual build. You could reduce any sheer forces by resting the cross
members on top of the inside frame support. This shouldn't make much
difference given the amount of force exerted by the ends of the tank. This
bracing keeps the whole thing square. There are braces on each end and one
in the middle, both top and bottom. 
I covered the frame with 3/4" Oak Plywood and created a face frame on the front for the future cabinet doors. It took a couple of hours to cut the plywood and attach it all. I would suggest having a helper around when you start to cut the plywood. It's heavy and expensive, so you don't want to make any cutting mistakes. Everything is attached to the frame with screws except the front vertical face frames. Those are glued on. Be cautious with the cutting plan for the plywood. Miss a cut and spend another $50 on a second sheet of plywood. I didn't miss. I have an 8' x 8" piece left over. Not enough to use on the doors though, unless I glue them together. I may do that and get solid oak for the rails and stiles. You'll need a router and a biscuit joiner to make the doors easily. I think you might be able to order them from a cabinet maker or even your local hardware store if you make them yourself.
At this point I have completed construction. In the picture above you can see that the top screws in the front are a couple of inches down from the top. I was planning at this point to use a 3-4" baseboard molding around the top and that would cover these. I ended up liking the corner molding around the top so much better, I filled these with wood putty to hide them and used the 1-1/8" corner molding around the top.
Don't worry about the gaps between pieces. We'll cover those up with
the molding around all edges.
I applied two coats of Pecan stain to the plywood, sanding after each coat. Then I applied 3 coats of polyurethane and sanded with 600 grit paper between each coat. I stained the entire piece separately from the molding. After everything was stained, I attached the molding with a pneumatic brad nailer. The polyurethane will protect the piece from any water that gets on it. The gloss makes it nice and shiny and feels like there's a layer of glass protecting it. I let each coat dry overnight so I did the whole thing in the evenings after work. I chose the pecan colored stain because our house is old and all of the molding and cabinets are dark walnut. I wanted to brighten up the room some but didn't want to contrast too much as I would with an Oak colored stain, that was just too light in color. By the way, it might be prudent at this point to mention that you should include your wife in decisions like color and style. This will keep her happy and involved in the process, especially in those areas that most of us men aren't quite as good at. If it's a team project, it's more likely to be funded.
There's not enough plywood left to use on the doors unless I glue them together side to side. I may do that and get solid oak for the rails and stiles. You'll need a router and a biscuit joiner to make the doors easily. I think you might be able to order them from a cabinet maker or even your local hardware store if you don't want to make them yourself. It looks nice without doors so they are an option. I plan on using the 29 gallon tank below for a breeding/fry growout tank, so it may not be presentable all the time. I also want the ability to remove the doors entirely once I have them. In order to do that, you must find a hinge that is a "lift off" hinge and if you make the doors larger than the opening you'll need face frame lift off hinges. http://www.vandykes.com/product/02012011/
DIY Background
There are many resources on the net for nice 3D inside the tank
backgrounds. I have learned so much from reading all the posts at http://www.cichlidforums.com
Here are a few site that I've found very helpful.
Example
1
Example
2
Example
3
Example 4 (good
instructions)
Example
5
Example
6 (this is similar to what I'm planning)
Info
1
Info
2
Once I get going on the background, I'll move this info to that page.
Sure hope this is of help to some folks. I sure enjoyed making it and I think it looks as good as these.