If you are designing a hood for an aquarium or repairing a broken hood, you need to install a light reflector. The reflector takes the florescent or incandescent light emitted from the bulbs and forces the light downward into the aquarium. If you do not have a reflector, the hood will look ornamental but not be functional. You can purchase reflectors, but often they are either too large to fit or too small to be effective.
Measure the length and the width of the aquarium light hood with a tape measure or ruler. For example, a common light hood for a 10-gallon aquarium is 12 inches long and 3 inches wide.
Cut a piece of highly polished 1/16-inch aluminium sheet to the measurement you took with a pair of tin snips or a band saw. A band saw produces the cleanest edges.
Lightly sand any rough edges of the aluminium with a fine-tooth bastard file
Scuff the unpolished side of the aluminium with 600-grit sandpaper to give the adhesive something to which it can adhere.
Remove the incandescent or florescent bulbs to gain access to the gluing surface of the hood. The reflector goes between the inside top of the light and the light bulbs. With the bulbs removed, it becomes easier to glue the reflector to the inside surface of the hood.
Coat the scuffed surface of the aluminium with a thin layer of epoxy or glue. Coat the entire surface to ensure proper adhesion.
Place the scuffed side of the aluminium into the hood and press it into place. Press from the centre of the aluminium and work your way to the outside edges to squeeze out any excess glue or epoxy. Wipe the excess away with a damp rag. Allow the epoxy or glue at least 24 hours of drying time before utilising the hood.
Highly polished aluminium sheet stock is available at most home improvement stores.