Orlushy 800W Submersible Aquarium Heater with Intelligent LED Temp & Watt Display and External Controller, Frequency Conversion Fish Tank Heater for 55-200 Gallon Tanks (800W for 100-200Gal) Nova ...

Better still, just mount them outside of the tank and sense the water level directly through the glass. You can get 12 volt ones used off of ebay no problem for awfully cheap. Interface to an ...

The Aqueon LED 20 Aquarium Kit comes with everything you need to start a new fish tank, including a heater and thermometer. Best betta fish tank: Fluval Flex Aquarium Kit - See at Amazon ...