Introduction
Thank you for choosing the boxtech Small Fish Tank Heater. This submersible heater is designed to maintain a stable and optimal temperature for your aquatic pets in tanks ranging from 3 to 12 gallons. Featuring an external temperature controller, LED digital display, and advanced safety features, this heater provides reliable and convenient temperature management for various aquatic environments, including fish tanks, betta tanks, and low-water level turtle tanks.
Product Features
- Compact Design: Small tank heater suitable for 3-12 gallon aquariums with a 5.35ft power cord.
- Adjustable Temperature: Temperature can be accurately adjusted from 68 to 93°F (20-34°C).
- Safety Protections: Intelligent induction unit with auto memory function, featuring E1 (anti-dry protection) and E2 (overheating protection) fault codes.
- LED Digital Display: Easily monitor real-time temperature and error codes.
- External Controller: Adjust temperature without getting your hands wet.
- Energy-Saving & Fast Heating: Thickened explosion-proof quartz tube design with metal-ceramic heaters for efficiency and durability. Maintains constant temperature after 72 hours of continuous heating.

Figure 1: Key features of the boxtech aquarium heater, including its ABS anti-scald housing, strong suction cup for firm installation, liquid crystal display for temperature at a glance, and durable metal ceramic + quartz heaters.
Package Contents
- boxtech Mini Aquarium Heater (Model: BT-G50)
- External Temperature Controller
- Suction Cups for mounting
- Instruction Manual
Safety Precautions
- Ensure the heater is fully immersed in water before plugging it in.
- When performing water changes or maintenance, turn off the power and allow the heater to cool for at least 15 minutes before removing it from the water.
- Do not bury the heater in sand or mud.
- For fish tanks, immerse the heater vertically. For turtle tanks with low water levels, the heater can be placed horizontally.
- Keep the power cord and controller away from water splashes.
- Regularly inspect the heater for any signs of damage. Discontinue use if damaged.

Figure 2: Important installation precautions, showing the heater must be fully immersed in water and turned off for 15 minutes before water changes. Incorrect partial submersion or burying in sand is also shown.
Setup Instructions
- Placement: Choose a location in your aquarium where water flows freely to ensure even heat distribution. Avoid placing the heater directly in substrate (sand or mud).
- Mounting: Use the provided suction cups to securely attach the heater to the inside wall of your aquarium. Ensure the heater is fully submerged in water.
- Orientation: For fish tanks, position the heater vertically. For turtle tanks with low water levels, the heater can be placed horizontally.
- Connect Power: Plug the heater's power cord into a suitable power outlet. The LED display on the heater will illuminate, showing the current water temperature.

Figure 3: The boxtech aquarium heater installed vertically in a fish tank, showing its compact design and digital temperature display.

Figure 4: Illustration of optimal heater placement within the aquarium to ensure even temperature distribution with water flow.
Operating Instructions
- Power On: Once plugged in and fully submerged, the heater will display the current water temperature.
- Setting Temperature: Use the external controller to adjust the desired temperature.
- Short press the button on the controller to increase the temperature.
- Long press the button for 3 seconds to toggle between Celsius (°C) and Fahrenheit (°F).
- Temperature Stabilization: It may take 48-72 hours for the water temperature to fully stabilize throughout the tank, especially in larger volumes.

Figure 5: The external controller allows for easy temperature adjustment and switching between Celsius and Fahrenheit by long-pressing the button.
Video 1: Demonstrates the boxtech aquarium heater's temperature sensing and setting functions, including the E1 error for low water level and the process of adjusting temperature with the external controller. Shows the heater in action within an aquarium.
Video 2: Highlights the miniature size of the boxtech aquarium heater, its unique design, and the ease of adjusting temperature by long-pressing the controller button to switch between Celsius and Fahrenheit. Also shows the E1 error for low water level.
Maintenance
- Cleaning: Periodically clean the heater surface to prevent algae buildup, which can affect heating efficiency. Always unplug the heater and allow it to cool before cleaning.
- Water Changes: Before performing water changes, always unplug the heater and wait for at least 15 minutes to allow it to cool down. This prevents thermal shock and potential damage to the heater.
- Inspection: Regularly check the power cord, heater body, and suction cups for any signs of wear, cracks, or damage. Replace the unit if any damage is observed.
Troubleshooting
| Fault Code | Account For | Cure |
|---|---|---|
| E1 | Anti-dry protection (Water level too low, heating rod not fully immersed) | Simply immerse the heating rod completely into the water. |
| E2 | Overheating protection (Sensor open circuit) | Take the heater out of the water and put it back in when the error code appears. |
| E3 | Overheating protection (Water temperature in tank is too high) | Turn the heating rod off or turn the temperature down until the water temperature returns to normal. |

Figure 6: Visual guide to troubleshooting common error codes (E1, E2, E3) displayed on the heater, along with their causes and recommended solutions.
Specifications
| Feature | Details |
|---|---|
| Model Name | BT-G50 |
| Power | 50W |
| Input Voltage | 110-120V/60Hz |
| Applicable Aquariums | 3-12 Gallons |
| Temperature Range | 68-93°F (20-34°C) |
| Power Cord Length | 5.35 ft (64.1 inches) |
| Item Dimensions (L x W x H) | 4.7 x 1.3 x 0.7 inches (approx.) |
| Item Weight | 8.4 ounces |
| Material | Thickened explosion-proof quartz tube, metal-ceramic heaters, ABS anti-scald housing |

Figure 7: Detailed specifications for the boxtech aquarium heater, including power, voltage, tank capacity, temperature range, and dimensions for various models.
Warranty and Support
This boxtech aquarium heater comes with a 6-month warranty from the date of purchase. This warranty covers manufacturing defects and malfunctions under normal use conditions.
For warranty claims, technical support, or any questions regarding your product, please contact boxtech customer service through the retailer's platform or visit the official boxtech store page:
Please have your purchase details and product model number (BT-G50) ready when contacting support to ensure a quicker resolution.