I will update this as time allows, but for now I want to put down the basics on the how to.
Making your own aquarium can be much cheaper than buying one if you plan to make a tank at least 75g or larger. There are a number of ways to go about it but I will focus on the easiest way for the average Joe.
Most people will build their tanks from plywood because it is cheap, easy to use and easy to find. What you want to do is make a 5 sided box out of plywood. On the sides you plan to have view through you need to leave a 2" overlap of wood for your glass to be supported by. You will need to cut out the "windows" prior to assembly. Once you have all four sides and the bottom cut out you need to assemble them. You will need to use glues and screws for this task. 2"-2.5" screws will work for this as well as wood glue. Using clamps or tape put the frame together, then using pencil make every 3" about 1/2 the width of the wood from the edge, these will be the spot you will put your screws. Next you want to predrill or pilot the holes with a drill bit smaller than the screws you are using. Once you have all the holes drilled you need to take the frame apart. Apply glue to the contact edges that you just drilled and then screw the pieces of the frame together one at a time, only put glue on the pieces you are working with, you dont want it to start drying until it will be completed. Make sure to wipe of excess glue, its tuff to remove once dry. I recommend starting with the bottom and one of the small sides, then do the other side, then the back and finally the front. Make sure not to overtighten screws and strip or crack the wood. It is very important that you make your tank square and true. You need to let the glue dry for the manufactures min time before proceeding. I suggest using cabinet grade plywood so that both sides are finished and smooth. !/2" thick is fine for all tank sizes under 22" of depth, 3/4" should be used for taller tanks. Keep in mind that you need to paint or stain the frame prior to installing the glass so that it will have a backround.
I believe the easiest, cheapest and quickest way to seal a tank up is with acrylic sheets. You will need thin acrylic to do this, 1/8" thickness is good. You will put a piece in the bottom first, then the back, and if your sides arent see through, the sides next. Once you have your acrylic sides in place you need to use Aquarium Safe glue and apply a generous bead of glue to all the seems, then using your finger smooth the bead and make sure that there is no gaps in the glue. Dont be afraid to use too much glue. Let that dry for 2 days before continuing on. Now measure for the pieces of glass you will need. The sides will go in between the front and rear panels, measurements need to be exact, when you place your order for the glass, make sure to give yourself about 1/16"-3/32" fudging room, so make the measurements that much smaller. Once you have all your pieces you will glue them in place and let them dry for 2 days.
Glass or Acrylic thickness needed for the viewing windows is dependant on tank depth
Tank Height: Minimum Glass Thickness:
These are what manufacturers are currently using
Next as you all know aquariums bow from water pressure. You need to go and purchase 3/32"-1/8" thick 2" wide stainless steal sheet metal to brace with, for tanks 4 feet long one brace, 6ft long 2 braces, 8ft long 3 braces, and so on. You want to evenly spce your braces out. they will sit on the top of the tank and you will drill two holes in each end of the metal and then using screws attach it to the top of the tank. These braces will also help support your hood or canopy for the tank. Make sure to use stainless steel here with stainless screws as well.
There are many ways to go about this. I recommend making multiple lids as opposed to one larger one. If you choose to use acrylic use 1/4" thick or it will bow severely, use lexan acrylic for this, it is much stronger. If you wish you can drill your braces to put pins through the acrylic to keep the lids in place.
If you want a predrilled tank you need to do this at the end of the project. Buy all your bulkeads needed so you will know the hole sizes you will be using. Drill from the inside out. After the holes are drilled you will need to sand the rough edges off. I also recommend lifting the acrylic slightly and putting some aquarium glue between the wood and the acrylic to prevent wood warping if the bulkhead was to leak. Next install all your fittings.
I recommend only drilling the back, and drilling where you want the tank height to be and using pvc to make tubes that the water will drain through instead of the traditional overflows that maufacturers use.
Feel free to ask questions and if I dont see them PM me and tell me to look at your question.
It really is easy to do if you have good carpentry skills and have access to the tools needed (Circular saw, hole saw, electric drill and bits, screws and glues)
Here are some rough costs:
4x8 sheet of 3/4" birch plywood $50
4x8 sheet of 1/2" birch plywood $40
Large tube of Aquarium Safe glue $10
3lb box of screws $7
Acylic and Glass prices vary greatly, call around to find your areas best prices, ask for salvage glass if you want cheaper glass
* Very important to note that you should test fill these tanks outside. Fill them all the way up and let it sit on level ground for about 2 days or so to monitor whether it sprouts a leak or not, keep in mind water will be lost to evaportation too!*