Using the Marina Submersible Aquarium Heater is a breeze. First, decide on the right power rating for your aquarium size. Then, use the suction - cup bracket to securely attach the heater to the side of the tank. Make sure it's fully submerged in water. Next, use the easy - to - access temperature set dial to set the desired temperature within the 20° C to 28° C (68° F to 82° F) range. Check the on/off pilot light indicator to see if it's working. As for maintenance, regularly clean the heater to prevent algae buildup. Also, inspect the glass for any cracks or damage. When not in use, unplug it from the power source and store it in a dry place. Always ensure the heater is turned off before performing any maintenance tasks. Keep in mind that the bumper guard is there to protect your fish, so don't remove it. With proper use and care, this heater will serve you well for a long time.