hygger 100W Submersible Aquarium Betta Heater with Digital LED Display Temperature Controller, Small Aquarium Fish Tank Heater for Freshwater & Saltwater up to 40-80L

• 【Small Yet Powerful】This 100W aquarium heater measures just 5.35 inches, ideal for 40-80L (10–21 gallon) tanks. Red light indicates heating; green light means constant temperature. Suitable for marine, saltwater, freshwater, fish, turtle, and betta tanks as well as small ponds. Please select the correct wattage using our size guide
• 【External Digital Controller】Adjust temperatures via an external controller without getting hands wet or disturbing tank water. Adjustable range: 15–34°C (59–93°F). The display shows both current and target temperatures, and you can switch settings easily with one press. No separate thermometer is needed
• 【Overheat Protection & Memory Function】The unit shuts off and flashes “EE” if water temperature exceeds 35°C (95℉) to prevent overheating. It also saves your last temperature setting; after a power outage, it restarts with your original preferences automatically
• 【Dry-Run Protection】The aquarium heater automatically stops heating and flashes “Er” when lifted out of water. It resumes operation immediately once fully submerged, providing reliable safety for daily use
• 【Durable & Efficient Heating】Made of shatter-resistant quartz glass, this fish tank heater is safe and long-lasting. The high-efficiency nickel-chromium heating element and silicon carbide conduction deliver consistent, even heating while maximizing energy use

Product description hygger Submersible Aquarium Heater 100W Product Features: LED digital temperature display: Multi-function LED digitadisplay shows the water temperature clearly and accurately. External temperature controller and out of water protectionfunction: Easy to use and set the desired temperature. Theheating rod will stop working and show an error code “Er" when outof the water. Memory Function and shut-off automatically: The memoryfunction can maintain the setting when the power is back on. lt willstop heating after reaching the set temperature. Explosion-proofquartzheating tube: Explosion-proof andinsulation the quartz tube is safer than traditional coil heaters. Caution: Place the hygger heater fullysubmersible when it's on, unplug itand wait for 15 minutes beforechanging the water or removingthe heater.Please ensure enough water flowand water circulation in your fishtank when using the heater Directions Before use, ensure that the power of the heater matches the water volume of the aquarium. Connect the power supply only after fully submerging it in water; dry heating is strictly prohibited. Adjust the temperature dial as needed. It is recommended to use a thermometer to monitor water temperature to avoid abnormal temperature. Secure it in a location with good water flow in the aquarium to ensure even heat distribution.