External heaters remove the need for bothersome heating elements in the aquarium and are safe because the electricity stays outside. The installation could not be easier: Cut through the filter hose, place the heater in between, set the temperature - done!
You can read more about the external heaters e300 and e500 here JBL PROTEMP e300 and JBL PROTEMP e500
You can read more about heaters in aquariums in our Themeworld: Heating and cooling