DIY - Plywood/Glass Aquarium

I had very little experience building anything prior to attempting this type of project. I researched as much as I could find on the internet and through discussion groups. Once I felt I had all I needed, I jumped right in and tried to make my tank as fast as possible. (Hint: taking your time is best) One smart thing I did, was planning on building a small version of my tank first. The theory being, if it leaks, I won’t have a ton or more of water on the floor.
This article is intended to be used after reading the original plans for the plywood aquarium. Some information will be repeated, but it will be easier to go through step by step. My most important advice is patience. If you don’t rush, and focus on doing the job right, your tank will work the first time.
The first step is to draw up plans for a tank: what are the dimensions you wish for the tank? The GARF website has a great program to give you your cut list when you enter your future tank dimensions. A couple important facts for glass thickness. If your tank height will be 18 inches or less, ¼ inch glass is fine. 18 – 24 “ tank height requires 3/8 “ thickness and 24 – 36” tank height requires ½” glass. It isn’t recommended to make tanks taller than 36” (at least with these materials). As long as the tank itself is well supported, the overall number of gallons will not influence this, as the overall height of the column of water and it’s weight is the important factor. ¾ inch exterior grade plywood is your other basic building material.
Now that you have your tank dimensions and materials list (see other article) you can buy your supplies. Understand that this tank becomes cost saving at around 75-gallons. Everything is found at your basic hardware store (Home Depot/Lowes) with the exception of the epoxy. The important aspect of the two part epoxy paint is it’s future safety for your fish. Finding a paint that is potable is ideal. I think most epoxy paints should be ok, since it hardens into a hard plastic layer, however, not a step to take lightly. Sources for the paint include pool supply stores (swimming pool paint with curing agent), auto stores (look for marine/RV epoxy). I even have read of people using the Home Depot stuff, usually used for garages, etc. It does seem to matter if it is colored or not. I purchased mine online through a marine supply store. Mine was less of a paint, more of a bonding epoxy, but it worked well for my smaller tank, and painted on very easily.
Measure and cut your wood. Check the edges of the plywood for any defects/rough spots and fill with wood putty and sand smooth to optimize bonding surface area. I recommend measuring out your screw holes in your wood once it is all cut to fit (every 2-3”) and then pre-drill your holes (Note: take your time when drilling.) Several options are available to glue your panels together. I couldn’t find any resorcenol wood glue, but picked up some Gorilla Glue instead. This stuff is great, and quick drying. The major downside: not waterproof. Liquid nails is probably your best bet; not only does it glue your wood together, but basically acts as a second waterproof barrier. Glue your wood together and screw together as the other article directs. This is much easier if you have one or two others to help you out. As each piece is glued on, screw in all your screws – this eliminates the need for using clamps. Be sure to wipe all excess glue off, as this stuff is very hard to get out once dried. (Note: don’t screw/glue your internal brace on yet, you still need to get your piece of glass into the tank.)
Once you give the wood time to dry and set (24 hours), you can apply your epoxy paint. I can’t stress enough the need for a very well ventilated area to apply. An open garage is not good enough, even with a fan. This stuff is extremely toxic. Ten minutes close up to this stuff is enough to cause some serious harm. (Note: check your epoxy for optimum temperatures, it may not set well or take longer to dry outside the 50-75 F degree range.) Allow adequate time between coats. I found 48 hours much better than 24. Use a power sander with caution, it’s easy to remove the previously applied epoxy coat.
A note relating to your glass. Most likely, you will be ordering a custom cut piece, order the edges polished to avoid potential harm when installing. If you are making a smaller tank (glass not too heavy), have a way to place weight evenly distributed over the glass to ensure good compression of the silicone and avoid any gaps/air spaces. (Bags of aquarium sand/gravel work well for this). Once this is in place, place a thick bead of silicone around the interior edge of glass. I had never used/applied silicone before, but some tricks to having it come out neat. Use a wet finger or preferably a tool to push the silicone into the creases and remove all the air spaces. If you apply masking tape along the edge of where the bead is, when you push it down, remove the tape, giving you a nice clean border.
Another option to seal the inner corners of your tank, given me by one of our fellow members is to use fiberglass matting applied covering the inner edges ½ inch each border and then apply 2-3 coats of your epoxy paint. When dry, this forms a solid layer of waterproof “plastic” and effectively sealing your tank. You will still need to use silicone to seal the edges of the glass. I got my silicone from two places. Big Al’s Online store sells the big caulking tubes of aquarium safe silicone for a couple dollar each. Or you can go to your local hardware store and get GE brand clear silicone (avoid any with mildew resistant labels – toxic for fish). (Note: apply silicone in well ventilated area – Very strong vinegar odor.)
The labels on the silicone and the DIY sites all say allow the silicone to cure for 48 hours before filling your tank. I found this was not enough time, and although I had applied it properly, under water pressure, small channels were pushed out in the still malleable silicone, resulting in a leak. I recommend giving it 3-4 days (patience, remember) before filling. The fully cured silicone should be clear and have no more horrible odor. Just make sure to have the tank test filled in an area that can handle a leak. If your tank leaks, it will probably be very slow/minor, but better to be safe. I recommend having the tank filled for a couple days to check for leaks. Then you can set it up for real.
I hope this article is helpful. Once I made many mistakes, mostly from trying to rush the project, I found it was actually pretty simple and the results are a great tank. □