100w Water Heater This compact, submersible, 100 watt heater has a titanium heating element and can be used in both fresh and salt water. The external temperature controller can be set from 68 to 92°F. The titanium heating element is 1.5" in diameter and will not crack if dropped. A built-in temperature sensor will automatically turn the heater off if exposed to air. 100 watts, 1.5" x 3" x 44" x 6.6" Close up picture shows 200 watt version (MI121).