Introduction
This manual provides detailed instructions for the safe and effective use of your hygger Aquarium Heater 300W. Please read this manual thoroughly before installation and operation, and retain it for future reference. This heater is designed for maintaining optimal water temperature in freshwater and saltwater aquariums ranging from 40 to 80 gallons.

Image: The hygger Aquarium Heater 300W with its external digital display controller.
Product Features
- Power and Capacity: 300W heater suitable for 40-80 gallon freshwater and saltwater tanks.
- External LED Digital Display Controller: Allows for easy temperature setting and monitoring. Temperature range: 59-94℉ (15-34℃), accuracy: ±1℉/℃.
- Multi-Protection Design: Incorporates several safety features for enhanced reliability.
- Dual Temperature Control Chip and Probe: Ensures accurate temperature regulation and heating.
- Anti-Cooking Fish System: Automatically stops heating and alarms if water temperature exceeds 95℉ (35℃) to protect aquatic life.
- Anti-Dry Burning / Out-of-Water Protection: Heater automatically stops heating and alarms if not fully immersed in water.
- Low-Temperature Protection: Alarms if water temperature drops below 59℉ (15℃).
- Memory Function: Retains set temperature even after power interruption.
- Thickened Detachable ABS Guard: Provides protection for the heating elements and is easy to clean.
- Fast and Stable Heating: Features dual explosion-proof quartz heating rods and nickel-chrome wire for efficient and consistent heating.

Image: Diagram illustrating the multi-protection features of the heater.

Image: Precise temperature control system with intelligent probe and dual control chips.

Image: Demonstration of the heater's memory function after a power interruption.
Safety Instructions
Adherence to these safety guidelines is crucial for preventing electric shock, injury, or damage to the product and your aquarium.
- Always unplug the heater from the power outlet before performing any maintenance, cleaning, or handling the heater.
- Ensure the heater is fully submerged in water before plugging it in. Operating the heater out of water will trigger the dry-burning protection and can damage the unit.
- Do not place the heater directly on gravel or sand. Ensure it is suspended or attached to the tank wall using the provided suction cups.
- Verify that the power supply voltage (AC110-120V/60Hz) matches the heater's requirements.
- Do not use the heater if the power cord or plug is damaged.
- Keep the controller dry and away from water.
- This appliance is not intended for use by persons (including children) with reduced physical, sensory, or mental capabilities, or lack of experience and knowledge, unless they have been given supervision or instruction concerning use of the appliance by a person responsible for their safety.
- Children should be supervised to ensure that they do not play with the appliance.
- For indoor use only.

Image: The three-pin plug designed to prevent electric leakage and shock.
Package Contents
Please check the package for the following items:
- 1 x hygger Aquarium Heater (300W)
- 1 x LED Digital Display Controller
- 3 x Suction Cups
- 1 x Adhesive Hook
Setup and Installation
- Unpacking: Carefully remove all components from the packaging. Inspect for any damage.
- Heater Placement:
The heater must be fully submerged in water. It can be installed vertically or horizontally.
- Vertical Installation: Attach the heater to the inside wall of the aquarium using the suction cups. Ensure the water level sensor is below the water surface.
- Horizontal Installation: For shallow water tanks (e.g., turtle tanks), attach the heater horizontally to the tank wall. Ensure the heater is not placed directly on gravel or sand. Maintain at least 5cm clearance from the water surface to the top of the heater for proper operation of the water level sensor.

Image: Proper immersion and placement of the heater. The image illustrates both vertical installation for freshwater and saltwater tanks, and horizontal installation for shallow water tanks, emphasizing full immersion and avoiding placement on gravel.

Image: Strong suction cups for secure attachment to the tank wall.
- Controller Placement: Mount the external LED digital display controller in a dry location, easily accessible for temperature adjustments. Use the adhesive hook if desired.
- Power Connection: Once the heater is correctly positioned and fully submerged, plug the power cord into a standard AC110-120V/60Hz outlet.
Operation
The hygger Aquarium Heater features an external controller for easy temperature management.
- Power On: After plugging in, the controller will display the current water temperature and the set temperature.
- Setting Temperature:
Short press the "SET" button to adjust the desired temperature. Each short press increases the set temperature by 1℉. The temperature range is 59℉ to 94℉ (15℃ to 34℃).

Image: External controller interface. The image highlights the indicator light, water temperature display, set temperature display, and the 'SET' button for short presses to adjust temperature and long presses to switch between Fahrenheit and Celsius.
- Temperature Unit Conversion: Long press the "SET" button for 3 seconds to switch between Fahrenheit (℉) and Celsius (℃).
- Heating Indicator: The indicator light on the controller will illuminate red when the heater is actively heating and blue when it is in standby mode.
- Automatic Heating: The heater will automatically start heating when the water temperature drops 1℉ below the set temperature and stop when the set temperature is reached.
Maintenance
Regular maintenance ensures optimal performance and longevity of your heater.
- Cleaning: The thickened detachable ABS guard can be removed for easy cleaning. Unplug the heater, remove it from the tank, and gently clean the guard and heating elements with a soft brush or cloth. Do not use harsh chemicals.
- Inspection: Periodically inspect the heater and power cord for any signs of damage, cracks, or wear. Replace the unit if any damage is observed.
- Water Level: Always ensure the heater is fully submerged. Low water levels can trigger the dry-burning protection.

Image: Thickened detachable ABS shell for easy cleaning and maintenance.
Troubleshooting
The controller provides error codes and alarms to indicate specific issues.
| Error Code/Alarm | Description | Solution |
|---|---|---|
| "HH" and Beeping Alarm | Water temperature is higher than 95℉ (35℃) - Anti-cooking fish system activated. | The heater has stopped heating. Add some cooler water to the tank to reduce the temperature. The heater will restart when the water temperature drops below 94℉ (34.4℃). |
| "L1" and Beeping Alarm | Heater is out of water (water level sensor activated) - Anti-dry burning protection. | Unplug the heater, then fully immerse the aquarium heater in water. Ensure the water level is above the sensor. The heater will resume normal operation once properly submerged and plugged back in. |
| "LL" and Beeping Alarm | Water temperature is lower than 59℉ (15℃) - Low-temperature protection. | The heater has stopped heating. Check if the heater is functioning correctly or if the ambient temperature is too low for the heater's capacity. Ensure the set temperature is within the operating range. |
| Heater not heating | No heat output, but controller is on. | Check if the set temperature is higher than the current water temperature. Ensure the heater is fully submerged and the power cord is securely plugged in. If the issue persists, contact customer support. |

Image: Visual representation of Anti-cooking Fish Protection and Low Temperature Protection alarms.

Image: Water level sensor activating 'L1' alarm when the heater is out of water.
Specifications
| Feature | Detail |
|---|---|
| Model Number | HUS-HG147 |
| Power | 300W |
| Recommended Tank Size | 40-80 Gallons |
| Voltage/Frequency | AC110-120V/60Hz |
| Temperature Range | 59-94℉ (15-34℃) |
| Temperature Accuracy | ±1℉/℃ |
| Heater Rod Dimensions | 9.1" × 3.0" × 1.4" |
| Power Cord Length | 5.9ft (Heater to Controller) + 4.9ft (Controller to Plug) |
| Materials | ABS, Quartz, Nickel-chrome Wire |
| Color | Black |
| Item Weight | 2.14 pounds |
Warranty and Support
The hygger Aquarium Heater comes with a 2-year warranty from the date of purchase.
If you encounter any issues or have questions regarding your product, please contact hygger customer support. Please have your model number (HUS-HG147) and purchase information ready when contacting support.
For further assistance, visit the official hygger store on Amazon: hygger Store





