Both freshwater aquariums and saltwater aquariums can be classified into tropical water aquariums and cold water aquariums. If you own either a freshwater tropical aquarium or a saltwater tropical aquarium then you will require a heater for your aquarium. Tropical aquariums consist of fish that are from tropical areas such as Africa, America and Asia. These fish can not live in water that is below 74 degree Fahrenheit and in order to help them survive winters, heaters are required. Cold water aquariums do not require artificial heating without the temperature of the water goes below 15 degrees Fahrenheit.
Aquarium heaters that are available online and in the market are of two kinds mainly being heaters with and without thermostats. Heaters without thermostats are the cheaper heaters and are not recommended for beginners since these heaters have to be manually turned off. If the heater is left on for an extended period of time without monitoring the water temperature then the water can get too hot and kill the fish. Heaters with thermostats are sophisticated heaters that have a thermostat that automatically turns off the heat when the temperature reaches a set degree. The heater then restarts when the temperature drops below the desired temperature and the cycle of heating and cooling continues. Heaters with thermostat are generally available with an in built thermometer and if you are planning to buy a manual heater then it is recommended to buy a timer device with the heater.
Discus and other delicate fish often get burnt if they go too close to the heater and certain fish like large Cichlids or Pacus are known to break heaters which can cause casually due to electrical leakage in the water. Heater guards or heater covers provide protection from burns and casualties and are highly recommended if you have submersible or gravel heaters.
It is always recommended to have two heaters that split up the required wattage since this problems problems in case one heater gets spoiled as the second heater will still manage to heat the water. If you have just one heater then a back up heater is highly recommended in case there are any problems with the original heater.
Source by Richard Gilliland