For a freshwater aquarium you have to learn about main types of heaters for aquariums, also. Not to become a specialist but enough to know which heater is the best choice for your own aquarium. You should know that for a tropical freshwater aquarium it is needed one heater, at least. If one heater fails, the other is going to maintain the proper temperature for your fish to be safe, while you can replace the out of order heater.
There are there types of aquarium heaters: submersible heaters, non-submersible heaters, and undergravel heating cable.
As a general rule, you must take into account that are needed 5 watts of heater per gallon (e.g. a 30 - gallon aquarium needs 150 – watt heater).
The submersible heater is designed especially for being placed under water in your aquarium. It should be attached on the rear glass of the tank, in a diagonal line in order to heat the whole aquarium. You will always know exactly the temperature because the heater has an internal thermometer. You can set the temperature you want for the water by rotating the adjustment valve, and the heater is going to preserve the set temperature. The water should be at the precise temperature that your fish love. Probably you must read about the species of fish that you have, about the perfect environment for them if the shop assistant didn’t tell you too much about them. As an advice, you should remove a heater from the aquarium only after 20 minutes of pausing the system. Also, when you put a new heater in the water, you should wait 20 minutes before turning it on.
Non-submersible heaters are the oldest heaters of all and they are designed for being fixed outside the aquarium, fixed on the tank’s frame. A tube made of glass is going to be placed in aquarium’s water. It also has a valve for adjusting the temperature and it is placed outside the water. This type of heater does not have a thermometer and therefore you must check a few times the temperature before getting the right one for your fish.
Not all the heaters have internal thermometers and that’s why you have to buy a separate thermometer. It is absolutely necessary to have a thermometer for checking the temperature inside the aquarium. You must keep a constant and appropriate temperature for the sake of the fish. Thermometers are very cheap, they do not need an expensive investment. The shops can offer you many types of thermometers: 1.Traditional: hanging thermometers, stick-on thermometers, floating thermometers, 2. Modern: digital thermometers, wireless thermometers.
Obviously the heater is needed for your aquarium, but if it doesn’t have a thermometer included, you will have to buy thermometer too.