300 Watt THH-0300 Titanium +Sensor w/Guard (40-80 Gallon) - Finnex

This Heating Element Required a Heating Controller to Operate! - https://www.saltwateraquarium.com/hc-810m-digital-temperature-controller-up-to-800-watts-finnex/

The THH heater series are designed to be used with an external controller.  THH heaters have an internal sensor that detects when the heater tube is exposed to the air.   If the water level drops too low and exposes the heater, the power to the heater is turned off.  This prevents overheating of the aquarium and/or burning up of the element.  The heater cord has a signal box with LED status lights.  Green means the heater is functioning normally.  A red light indicates the low water switch has been tripped and the heater is not heating.  The heater is constructed of corrosion-resistant titanium, making it safe for freshwater and marine aquariums.  The titanium tube is virtually unbreakable and features a protective heater guard.  The out of water sensor is located where the cord meets the tube.

Please Note: Additional heating units may be required and discouraged from using in extraordinary setups (where warranty may be void) not limited to:  Applications outside of standard aquarium use, basement setups, garage setups, ponds, outdoor use, greenhouses, extreme temperature conditions, etc.