HC-820M Digital Heater Controller

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$24.00 $59.99

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The Finnex HC-820M is an advanced digital processor controller tused for monitoring and adjusting aquarium water temperature. A remote sensor is placed in the aquarium water, sending temperature data to the controller to avoid wild temperature swings. The sensor contains no bi-metallic contacts, so you don't have to worry about arcing, corrosion, or the sensor wearing out over time like you would with a lower quality temperature controller. Additionally, the remote sensor has an automatic power-off function that will cut power to the heating tube if the sensor is exposed to air, preventing your aquarium from overheating in the event of low water level. The controller's LCD screen boldly displays the current temperature and includes buttons for easy temperature adjustment by a tenth of a degree.

  • 3 Digit digital display and control
  • 1000 Watt max. output load with dual relay protection
  • Out of water sensor protection with audio alert
  • Overheating audio alert
  • Temperature-saving memory protection
  • Temperature steady low variance technology
  • 1/10th Degree temperature calibration
  • +/- 0.5 degree F high precision accuracy


**Note** The HC-820M is NOT compatible with the APEX controller series. The HC-820M is also not effective in monitoring and controlling temperature in low TDS / RODI water.



Voltage: 110V-120V

Control Range: 49.9°F-94°F

Accuracy: +/- 0.5°F

Control: 1/10th Degree

Max. Load: 1000 Watts

Sensor Cord: 32"

Power Cord: 66"


More Information
UPC 850006562275
WiFi No
Controller Type Heating Only or Cooling Only (Single Stage)
Temperature Range 49.9°F - 94°F
Power Cord Length 5 Feet
Additional Notes NOT compatible with the APEX controller series.
NOT effective in monitoring and controlling temperature in low TDS / RODI water.
Alarms Audible, Visual
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Product Questions

Why would a Finnex 820 Saltwater Temp Controller have a caution/warning that it’s not effective in low TDS/ RODI water?
Because it wouldn’t do well in a top-off container but would be effective in a saltwater reservoir or aquarium at 1.02x specific gravity?
Question by: Leo Yurek on Nov 19, 2023, 11:10 AM
The heaters use a TDS sensor to detect water where the cord connects with the heater. Freshwater may not contain enough minerals to be conductive, resulting in the heater falsely thinking it's out of water.
Answer by: Chad (BRS Staff) on Jan 18, 2024, 11:48 AM