HMX-S Heater w/ Digital Controller

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Heaters are by far one of the most important pieces of equipment on any reef tank. Finnex has been making high quality, compact electric, titanium heaters for years and allow you to create a safe and very stable temperature within the tank. The titanium body of the HMX-S heater is virtually unbreakable unlike glass heaters and are corrosion resistant.

The new and improved controller on the HMX-S series has been modernized, with a touchpad control interface, and a crisp LCD display, allowing you to know the temperature of your tank at a glance from across the room.

All HMX-S heaters now include a plastic guard to cover the heating element portion of the heater. That will help keep any equipment or livestock from coming into contact with the element and overall making a much safer environment within the tank.


Finnex HMX-S heaters come with an attached digital, touchpad controller that will allow you to precisely set the temperature within your aquarium. These heaters are great for fresh or saltwater aquariums that require a stable, and safe heating system. The HMX-S heaters will keep the temperature within a range of +/- 2 degrees from the set point and with the heating indicating LED you will know when the heater is producing heat or not. Additionally, Finnex digital heaters are equipped with memory. so in the event there is a power outage, your heater will resume your preset temperature settings at start up. Please note that the digital display reads in Fahrenheit.


Finnex HMX-S Heater Comparison Chart

Model Wattage Amp Control Range Tank Size Overall Length
HMX-S 50 50 .45 68 - 92 degrees 5 - 20 gal 5.75 inch
HMX-S 100 100 .9 68 - 92 degrees 21 - 30 gal 6.75 inch
HMX-S 150 150 1.35 68 - 92 degrees 31 - 60 gal 8.0 inch
HMX-S 200 200 1.8 68 - 92 degrees 61 - 80 gal 10.75 inch
HMX-S 300 300 2.7 68 - 92 degrees 81 - 100 gal 12.0 inch
HMX-S 500 500 4.5 68 - 92 degrees 101 - 120 gal 15 inch


HMX Owners Manual

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Product Questions

Can these heaters be recalibrated?
Question by: Fawn on Jul 16, 2016, 4:21 PM
Hi Fawn,
The HMX-s heaters cannot be calibrated, however if you ever do notice their temperature is off, just use it as a reference. In all honesty depending on what your reference for temperature is, the heaters are usually pretty accurate within a degree or two.
Answer by: Charlie on Jul 18, 2016, 9:56 AM
What wattage is recommended for 100 gallon tank
Question by: kevin d fairman on Jun 11, 2016, 4:15 AM
Great question!
we recommend 2.5-5 watts per gallons. 250-500 watt heater depending on the background temperature of the room.
Answer by: Connor on Jun 14, 2016, 4:37 PM
Is the LED display on these heaters water resistant? I had an older version of this heater, and it died after only a few weeks. Was told it was water damage to the controller, which was sitting on the side of my sump.
Question by: Ryan Braunberger on May 4, 2016, 10:46 AM
Great question!
This will have a plastic cover and may be able to prevent small splashes however this is not designed to be water resistant and if water is left on it or creeps through the connection will cause damage.
Answer by: Connor on May 4, 2016, 12:34 PM
Hello. Does the display just show the setting, or does it also show the actual temp of the water? In either case, how accurate is the display? (My current heater is set to 75 but the actual temp on two different digital thermometers is 77.)

Lastly, is the display pad waterproof?

Thank you.
Question by: OnalaskaBill on Apr 28, 2016, 12:26 PM
Great question!
The Display will be used to set the ideal temp, after a few seconds it will display the actual tank temperature. The display will be +- 2 degrees. Teh display is not water proof and will need to be placed with care. This is slightly water resistant but not proof.
Answer by: Connor on Apr 28, 2016, 1:46 PM