Instructions
Unplug the aquarium light fixture. This will prevent you from electrocuting yourself when you remove the light.
Take the light fixture off of the aquarium. This reduces the risk that the fixture will fall into the aquarium.
Remove the ballast splash guard, if applicable. This is a hard plastic piece that keeps water from splashing onto the ballast. The guard usually slides out from one end of the ballast.
Grasp the light bulb in one hand and the fixture in the other hand. Take care that you don't break the light bulb.
Turn the light bulb gently. If the light bulb is a traditional tube fluorescent bulb, you will only turn it enough so the pins on the end line up with the slots on the ballast. Pull down gently once the pins are aligned with the slots on the ballast to remove the bulb. If the bulb is an incandescent, compact fluorescent or a metal halide bulb, it will unscrew from the ballast.
Dispose of the bulb in accordance with local ordinances.
How to Remove an Aquarium Tank Bulb
If your fish tank light bulb has gone out or if it is beginning to look dim, changing it is necessary to ensure the health and beauty of your aquarium. A poorly lit aquarium can lead to your fish or other aquatic life developing diseases. It may also lead to poor water quality and dingy-looking water. The way you remove fish tank light bulbs varies slightly according to the type of light bulb that your aquarium ballast uses.