1. Introduction
The Aquael Inline Flow Heater is an advanced aquarium heating device designed for both freshwater and marine environments. This manual provides essential information for the proper installation, operation, and maintenance of your 300 Watt Aquael Inline Flow Heater to ensure optimal performance and the well-being of your aquatic inhabitants.
This heater features an exceptionally precise and durable design, encased in an impact-resistant plastic housing. It includes a built-in electronic thermostat for accurate temperature monitoring and control, along with a system to prevent overheating.
2. Key Features
- Tank Size Compatibility: Suitable for aquariums ranging from 25 to 160 US gallons.
- External Mounting Design: Eliminates the need for internal heaters, providing a clutter-free aquarium environment.
- High-Efficiency Heating Element: Ensures rapid and effective water heating, maintaining stable conditions.
- Precise Temperature Control: Allows setting and maintaining water temperature between 20°C and 33°C (68°F to 91°F) with an accuracy of +/- 0.25°C (+/- 0.9°F).
- Durable Construction: Built from high-quality materials for reliable performance and longevity in aquatic environments.
- Overheating Prevention: Multiple temperature sensors prevent overheating and automatically turn off the heater if there is no water flow.
- LED Indicators: Displays both the current and set water temperature for easy monitoring.
- One-Touch System: Convenient heater control with a single button.

3. Setup and Installation
Proper installation is crucial for the safe and efficient operation of your Aquael Inline Flow Heater. Please follow these steps carefully:
- Placement: The heater is designed for external mounting. It should be installed on the outlet side of your external canister filter. This placement ensures that the temperature sensors and heating element remain clean and maintain optimal performance by receiving a consistent flow of filtered water.
- Hose Connection: The heater includes two different sizes of compression fittings for compatibility with a wide range of canister filters (1" OD & 3/4" ID, and 7/8" OD & 5/8" ID). Select the appropriate fittings for your filter's hose size. Securely attach the heater to the filter's return hose, ensuring all connections are tight to prevent leaks.
- Mounting: The heater offers multiple mounting options. It can be installed on the glass of an aquarium using the provided suction cups, or inside an aquarium cabinet using the screw holes (screws not included). The heater mounts can rotate 360 degrees for easier access to controls and monitoring, especially in tight spaces.
- Power Connection: Once installed and all connections are secure, plug the heater into a suitable power outlet. Ensure a drip loop is formed with the power cord to prevent water from reaching the electrical outlet.


4. Operating Instructions
The Aquael Inline Flow Heater is designed for user-friendly operation with precise temperature control.
- Power On: After successful installation, plug the heater into a power outlet. The LED display will illuminate.
- Setting Temperature: Use the one-touch button to adjust the desired water temperature. The temperature can be set within a range of 20°C to 33°C (68°F to 91°F). Each press of the button will cycle through the available temperature settings.
- Monitoring Temperature: The LED display indicates both the current water temperature and the set temperature. This allows for easy monitoring and verification of the heater's operation.
- Automatic Regulation: The built-in electronic thermostat will automatically regulate the heating element to maintain the set temperature with high accuracy (+/- 0.25°C or +/- 0.9°F).
- Safety Features: The heater is equipped with multiple temperature sensors to prevent overheating. In the event of insufficient water flow or excessively high temperatures, the heater will automatically shut off to protect your aquarium and its inhabitants.
5. Maintenance
Regular maintenance ensures the longevity and efficient performance of your Aquael Inline Flow Heater.
- Cleaning: Periodically inspect the heater for any buildup of algae or debris. Disconnect the heater from power and remove it from the filter line before cleaning. Use a soft brush or cloth to gently clean the exterior. Do not use harsh chemicals or abrasive materials.
- Hose Connections: Regularly check hose connections for any signs of leaks or wear. Ensure all fittings remain tight.
- Sensor Cleanliness: As the heater is installed on the outlet side of the filter, its sensors are generally kept clean by the filtered water. However, during filter maintenance, it is advisable to quickly check the heater's inlet and outlet for any obstructions.
- Power Cord: Inspect the power cord for any damage or fraying. If any damage is observed, discontinue use immediately and contact customer support.
6. Troubleshooting
If you encounter issues with your Aquael Inline Flow Heater, refer to the following troubleshooting guide:
- Heater Not Turning On:
- Check if the power cord is securely plugged into a working electrical outlet.
- Ensure there is proper water flow through the heater. The safety mechanism may prevent operation without adequate flow.
- Temperature Inaccurate or Fluctuating:
- Verify that the heater is installed on the outlet side of the filter, ensuring consistent water flow over the sensors.
- Ensure the heater's sensors are clean and free from debris.
- Confirm the set temperature on the LED display.
- Heater Overheating or Shutting Off Unexpectedly:
- This is often due to the built-in safety feature. Check for blockages in the filter or hoses that might restrict water flow through the heater.
- Ensure the ambient room temperature is not excessively high, which could contribute to the aquarium water temperature.
- Leaks at Connections:
- Tighten all compression fittings.
- Ensure the correct size fittings were used for your filter hoses.
- Inspect O-rings and gaskets for proper seating and damage.
If these steps do not resolve the issue, please contact Aquael customer support for further assistance.
7. Technical Specifications
| Specification | Detail |
|---|---|
| Model Name | Inline Flow Heater |
| Item Model Number | 132019 |
| Power | 300 Watt |
| Tank Size Compatibility | 25 - 160 US Gallons |
| Temperature Range | 20°C - 33°C (68°F - 91°F) |
| Temperature Accuracy | +/- 0.25°C (+/- 0.9°F) |
| Item Weight | 1.39 pounds |
| Package Dimensions (L x W x H) | 13.11 x 5.04 x 3.5 inches |
| Color | Black |
| Specific Uses | Indoor Aquarium Heating |
| Included Components | Heater, Manual |
8. Warranty and Support
The Aquael Inline Flow Heater comes with a 2 Year Warranty from the date of purchase. This warranty covers manufacturing defects under normal use conditions.
For warranty claims, technical support, or any questions regarding your product, please contact Aquael customer service. You can find more information and contact details by visiting the official Aquael store: