Although most aquarium tank lids are not overly expensive, it is still a good idea to replace the light ballast when it stops working. If the light flickers excessively when you turn the light on or the light does not power on at all, it is time to replace the ballast. Basic household tools are needed to change the ballast and a very basic understanding of electricity is needed. However, changing the ballast is not an overly difficult process.
Remove the florescent light bulb from the aquarium bonnet by rotating it counterclockwise. There are two pins on each end of the light. Those pins line up with the grooves on the ballast brackets. With the pins lined up, pull the light out of the ballast brackets.
Remove the Phillips screws that secure the reflector plate to the inside of the aquarium bonnet and then lift the reflector plate out of the bonnet.
Remove the ballast brackets from the reflector place by pulling outward on them. They are not bolted into place; they snap on. These brackets are not reused because they are hard-wired to the ballast. The new ballast is equipped with new ballast brackets.
Remove the wire nuts that cover the wire connections between the ballast and the electrical switch. Write down which colour wire connects to each side of the switch. One wire is black and one wire is white. The new wires connect in the same manner.
Remove the bolts that secure the ballast to the bonnet. Place the new ballast into the bonnet and secure it into place using the old bolts.
Connect the white wire and the black wire to the electrical switch and secure the wire nuts into place.
Place the ballast brackets onto the ends of the reflector shield. Continue to push inward on them until they snap into place.
Place the reflector into the bonnet and secure it using the old bolts.
Place the pins located on each end of the florescent light into the grooves on the ballast brackets and turn the light clockwise to secure it into place.