<b>hygger 500W 800W titanium steel aquarium heater with an external controller, with digital displays on the heater and the controller,<br>fast heating up and energy saving, perfect for use in large fish tank over 60 gallons in cold weather.</b><br><br> <b>Why choose hygger aquarium heater for large fish tank?</b><br> 1. Safe to use, the digital aquarium heater will auto shut off when the water temp is over 97℉, auto shut off when the top of the heater is<br> out of the water over 0.8inch.<br> 2. No explosion, with a plastic guard, the heating element is high-quality durable titanium steel, can be used for fresh water and saltwater.<br> 3. Energy saving, with 2 heating up modes, the MAX heating mode and the ECO heating mode, it will automatically shift according to the <br>D-value between the water temp and set temp.<br> 4. Digital display, you can check the water temp, set temp and the heating up mode on the controller at any time.<br> 5. Easy to set temp, only one set button on the controller, to choose the temp from 70℉ to 94℉ by pressing the button again and again, <br>only round number can be chose.<br> 6. Automatical thermostat, the submersible heater will stop heating when it reaches the set temp, and start ECO heating mode when the<br> water temp drop off 0.5-1℉.<br><br> <b>2 size available:</b><br> 500W for fish tank 60-120 gal<br> 800W for fish tank 120-180 gal<br><br> <b>Cautions for use:</b><br> 1. Please install the heater fully under water, but don't bury it in sands.<br> 2. Please unplug the heater and wait it to cool down for about 5-10 mins before you doing water change or moving the heater.<br> 3. We suggest to slip the suction cup clip to the top 1/3 of the heater tube.<br> 4. Please install the submersible fish tank heater vertically under water where close to the water intake.<br> 5. Please use wave maker or a circulation pump for the fish tank, the good water circulation will help uniform dispersion the heat produced by the heater.