There are currently two main structures of popular fish tank heating rods. One is to directly control the temperature with Bimetal, the other is to use thermistor to detect the temperature and use silicon controlled rectifier to control the on-off of heating rod. The longer the length of the heating rod, the better, under the conditions that the water level in the fish tank allows! Because the longer the heating rod, the more its heating surface it has! The more surfaces for heat energy exchange! The shorter the time for heat exchange!

Also, if using a 300W heating rod in your fish tank can meet the heating requirements of the tank, then I suggest using two 150W or 200W heating rods so that there won't be a tragedy caused by the failure of the heating rod and your negligence when there is only one heating rod! Preparing two heating rods ensures the temperature requirements of your beloved fish, considering that they will not malfunction at the same time! The difference in power consumption between two 200W heating rods and one 300W heating rod is not significant! (Under the same environmental temperature and insulation conditions) I have tested this with a dedicated energy meter!

There is also a lot of debate about the brand of heating rods. Some people believe that an imported product has high accuracy and long service life for constant temperature control (some fish friends use it for more than 6-7 years, which is still good), while others believe that it is more energy-efficient, but of course the cost is high. Additionally, some people believe that the difference in electricity saving for imported heating rods is also very small (isn't it a big deal to save 1 kilowatt hour of electricity per month?). In terms of reliability, one imported heating rod with a value of over 100 can buy N domestically produced brand fish tank heating rods at affordable prices. Even if the imported products can last for 5 to 6 years (you may not be sure), it is not as reliable as replacing them with a domestically produced one year.