Hygger compact aquarium heater is very safe and durable, milky quartz material made, can resist a high temp of 1800℉, excellent in explosion-proof & shatter-resistant.<br>The service life can be more than 3 years if only using in fresh water.<br><br><b>Led indicator light inside the quartz tube.</b><br>When the tank heater is heating, the indicator light is red. When it stops heating, the light is off.<br><b>When does the heater stop and restart heating?</b><br> The aquarium heater is very reliable to maintain the water temp as your set. It will stop heating when the water temp is 1.5-2℉ above <br>the set temp and will restart heating when the temp is 1.5-2℉ below the set temp.<br><b>Over heat protection</b><br>The aquarium heater will auto shut off once the water temp is over 97℉, a spare circuit in the controller will take work to turn it off in case of fault occurs.<br><b>How to adjust the temp?<br>?</b> Rotate the knob on temp controller to set the desired temp. Temp range is 75-91℉.<br><br><b>Size Chart</b><br>Power & Tank: 100W (10-30gallon) 300W (30-60gallon)<br>Heater Length: 8.5 inch 10.6 inch<br> If the room temp is lower than 50℉, please buy a larger wattage heater.<br><br><b>Do’s and Don’t’s<br></b>1. For better experience and aquarium safety, please carefully read and follow the user manual.<br>2. Keep the aquarium heater fully submerged in water.<br>3. Stick the heater horizontally onto the tank side near the water intake or on the way of water flow. <br>4. Don’t bury the heating rod in sand or stones.<br>5. Please keep the temp controller away from water.<br>6. Please don't connect the power before the heater is well installed.<br>7. Please wait the heating rod to cool down before you move the heater or change the water.<br><br><b>Specification:</b><br> Voltage: 100-120V <br>Frequency: 60HZ <br>Cable Length: 5.4ft<br>Warranty Period: 1 years<br><b>Package Includes:</b> 1 Aquarium Heater, 1 Shield, 2 Suction Cups, 1 User Manual