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Finnex HC-820M Digital Controller

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HC-820M Series Overview
1000 Watt Max Output Load with Dual Relay Protection
Out of Water Sensor Protection Audio Alert
1/10th Degree Temperature Calibration
3 Digit Digital Display & Control
Over Heating Audio Alert
Temperature Saving Memory Protection
1.5°F High Precision Accuracy
Temperature Steady Low Variance Technology
The HC-820M controller uses an advanced digital processor that monitors and controls the
water temperature in your aquarium. The heating controller receives temperature data from
the remote sensor in the aquarium. The remote sensor contains no bi-metallic contacts to
arc, corrode or wear out. This allows the HC-820M to have precise control, keeping the water
temperature stable while avoiding wide temperature swings common with low-quality aquar-
ium controllers. The controller displays the current temperature, allowing you to easily make
temperature adjustments on the front panel. Temperature can be adjusted by a tenth of a
The remote sensor also functions as an automatic power cut-off switch. If the water level
drops too low and exposes the temperature sensor to the air, power to the heater tube is
turned off. This prevents over-heating of the aquarium, saving your prized aquarium life from
harm or other hazards.
Maintenance: Secure the out-of-water sensor directly beneath the sensor cord clip,
without any cord slack, and above the heating element at all times. Clean and confirm
the out-of-water sensor is functioning properly every 30 days. Do not use heater if the
out-of-water sensor is inoperative. Refer to the instruction manual for proper maintenance and care

Customer Reviews

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Failed Feb 8, 2021
I purchased this controller to replace one that had a large swing. I installed this one around 12/22/20. Today is 2/8/21 and while doing my morning check I discovered my temperature had fallen to 75.3. I checked controller and the light was on to heat the water the heater was not even warm. So I plugged the heater directly into my Apex and the heater became warm almost instantly. Contacted Finnex and was instructed to plug a lamp into controller to make sure that it wasn't the heater. Anyway they want me to pay to send it to them so they can test and repair or replace. What a joke.