How to Build a Large Custom Aquarium

Written by nicole galipeau
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How to Build a Large Custom Aquarium
Custom aquariums are popular alternatives to store-bought versions. (Aquarium image by crossgolfing from

Custom aquariums are becoming more and more popular on the market due to their versatility in shape and size, and the fact that they can often be built for a lower cost than store-bought models. Large aquariums in particular can generally be constructed at a substantially cheaper rate than in stores, but careful planning needs to be done before the tank is constructed. Poorly built custom tanks can cause severe damage to people and property if they leak or break.

Skill level:

Things you need

  • Glass panels
  • Glass cutter (if cutting the glass yourself)
  • Aquarium silicone
  • Duct tape

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  1. 1

    Decide on the final dimensions of your custom aquarium to help determine the thickness of the glass and number of support braces you will need to use. Most aquariums less than 4 feet in length and 24 inches tall will be fine with standard 6mm aquarium glass and one central support. Anything larger than this should use between 10 and 12mm glass and at least one support brace every 3 feet to prevent bowing.

  2. 2

    Measure and cut the glass for the sides, or have the glass cut professionally at a glass supply or home improvement store. Be sure to explain your project plans to whoever cuts the glass, and stress the importance of clean, exact cuts and measurements. Even a few millimetres' error on the cuts can drastically weaken the integrity of the finished tank. Make sure to add the glass thickness (times two) to the length of the front and back panels when measuring so that they will be flush with the sides when gluing. For example, if the glass is 6mm thick and the tank is 20 inches long, your front and back panels should be 20 inches plus 12mm long.

  3. 3

    Arrange the cut pieces of glass on a large, flat surface, in the order that you will assemble them. A helpful way of arranging the pieces is to orient the side panels around the floor panel so that you can simply stand them upright to complete the tank.

  4. 4

    Run a bead of aquarium silicone all around the cut edge of the bottom panel of the tank, and along the cut edges of both of the short end panels. While the silicone should be around the entire bottom panel of glass, it needs only be placed on the sides of each end panel (not the top and bottom).

  5. 5

    Stand the side panels up in place quickly, pressing the silicone-beaded sides together to ensure a bubble-free union. Working with a partner can make this a much simpler task, and is necessary on larger tanks. All four sides should be joined up against the cut edge of the bottom panel, rather than on top of its face. The short side panels should be between the front and back panels, so that the cut edges are not exposed.

  6. 6

    Duct tape all sides of the aquarium in place.

  7. 7

    Attach the support braces by using silicone to attach 3-inch-wide strips of glass across the top of the tank, every three feet or so on tanks larger than 4 feet long. The supports should be glued so that they fit snugly inside the tank, about 1/2 inch from the top edge of the tank. You can also opt to run long support pieces the full length of the tank (called Euro-bracing), but this is generally considered optional for stability. Allow the supports and the tank sides to dry for at least 48 hours.

  8. 8

    Fill the tank slowly with water to test for leaks.

Tips and warnings

  • Use an old blanket or piece of carpet as a work surface to help prevent scratching your aquarium glass while you work.
  • While the beauty in building your own tank is in the rimless, European-style design, you can opt to add a glass lid to your aquarium by cutting glass panels to fit the top of the tank, and attaching a second, smaller piece of glass with silicone to act as a handle. Make sure that the panels are no larger than you can comfortably lift off the tank in order to gain access.

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