Instructions
Turn off the aquarium lights and remove the top. This gives you better access to the tank, and prevents damage to bulbs and light fixtures.
Follow the manufacturer's instructions for starting electric gravel vacuums. Some models run on batteries, while others require you to plug them into an outlet. Many simply require you to insert the nozzle into the aquarium and press the power switch.
Insert the tube on a manual gravel vacuum into the tank.
Determine where you will drain the water. You can drain the water into a bucket, sink or to the outside. Since this type of vacuum uses gravity, the point where the hose empties must be lower than the tank. The greater the difference in height, the faster the water will flow out.
Squeeze and release the bulb several times if your manual gravel vacuum is equipped with a one-way valve. The water will begin to fill the tube. Repeat this process until the water enters the hose and starts flowing downhill.
Place the entire tube and at least 3 feet of tubing into the tank if you are using a manual gravel vacuum without a valve. Make sure the tube and hose are completely filled, with minimal air bubbles. Large bubbles will break the siphon, causing you to start over. Cover the open end of the hose with your thumb, so the water cannot flow back into the tank. Lift the tube so the filled part of the hose drapes over the side of the tank and release the end of the hose.
Place the end of the hose in the bucket or sink. The water will begin to flow out of the hose into the container, drawing more water after it.
How to Start a Gravel Vacuum
Gravel vacuums used to clean home aquariums come in two types. Manual gravel vacuums consist of a stiff plastic tube attached to a flexible hose. Manual gravel vacuums drain the water out of the tank, while carrying the waste out with the water. This type of gravel vacuum is handy when you need to do a partial water change. They can be tricky to start, depending on whether they have a one way squeeze valve. Electric gravel vacuums return the water to the tank while collecting the waste in a bag or filter. Starting electric models is usually just a matter of pressing a switch.