Store-bought fish tanks are expensive. Making your own fish tank is a far more cost-effective way to provide a home for your fish. You can build a 125-gallon tank for large fish with a few simple materials. When fully operational and full of water, this tank will be very heavy and hard to move. Set up your tank in a permanent place in your home.
Lay the panes of glass on a flat work table. Using sandpaper, lightly sand all sides of the glass to file down any sharp edges. Apply acetone to a paper towel and wipe the glass down from about 2 inches to the edge. Using your scissors, cut about eight strips of duct tape. These strips should be about 6 inches long. Stick one end of each strip to your work table until you are ready to use the tape.
Label your glass pieces with your washable marker to remind yourself what pieces will go where. The three bigger pieces will be the bottom, front and back panels. The two smaller pieces will be the ends.
Lay the bottom panel in front of you horizontally. Take the back panel and a side panel and line them up in their appropriate positions along the edges of the bottom pane. Use two strips of tape to secure the back and side pane together. Stretch the strip of tape from one pane to the other. Repeat this step with the two other panes. You should have a glass rectangle box without a top. The strips of tape should be holding each corner firmly together.
Inspect the shape and alignment of the rectangle. Squirt a bead of silicone into one of the corners at the bottom of your tank. Follow along the crack, sealing the bottom edges together. Use your finger to push the silicone deep into the crack and leave a smoother surface. Repeat this process for all corners of the tank.
Let the silicone dry for a couple of hours. Use your razor blade to remove drips or messy silicone spots. After 48 hours of dry time, you may fill the tank half full to look for leaks. If it is completely sealed, carefully wash the tank to remove impurities.