Everything You Need To Know About Your Aquarium Heater Wattage Per Gallon

If you are a tropical fish hobbyist, heating your tank will be a crucial element in keeping your system thriving.  This is why we compiled this article with all the information you need to know about aquarium heaters and their wattage per gallon! 

Another reason you may need an aquarium heater is if you live in a cold climate.  Once temperatures begin to drop in the winter, you need to pay attention that your fish tank water remains at a certain temperature.  There aren’t that many cold-blooded fish species.  

Most species will need an average temperature of 75 degrees F.  However, according to North Carolina State University, “Most tropical fish can tolerate temperatures even in the low 60s or even high 50s for several hours”  But after this time period, you will need to adjust your temperature or else your fish risk dying.  

The exact temperature necessary depends on the fish type.  This is where knowing your aquarium heater wattage per gallon comes into play.

Aquarium Heaters and Size Calculator

One of the most important things you may be wondering is how to know which aquarium heater to use.  Typically, these heaters are a glass, tube-shaped device that you put in your tank or sump tank.  This tube is placed under the tank water where it is used to adjust the temperature.

Another kind of aquarium heater is a cable that you put underneath the gravel at the bottom of your tank.  This cable is connected to an exterior power supply which provides heat.  

If there is a problem with this cable, it will require you to remove all the tank contents to remove the cable to fix.  Due to the high maintenance required, this is not a highly recommended option.  

Aquarium heaters work by taking heat generated from electricity and transferring it to a coil which is wrapped within the glass tube.  The amount of heat that is transmitted is based on the setting you choose.  

But the maximum temperature it can reach is based on the aquarium heater wattage per gallon.  So how do you decide which heating capacity you need for your tank?  First, start out by choosing which fish you will raise.

Some fish like goldfish need a range of 68-74 degrees F.  While others such as the Betta Fish like between 76-85 degrees F.  You can see that there is a major difference depending on the fish type. 

So make your fish selection first before choosing the aquarium heater wattage per gallon. 

Determining Your Heater’s Watts Per Gallon

Another important consideration about what kind of heater you need is the size of your tank.  Based on the water volume, you can make a selection.

There is a general rule of thumb to follow.  For each gallon of water, there will be between 2.5-5 watts required for adequate heating.  So for example, if you have a 55-gallon tank you want a heater that is 275 Watts.  

However, these figures cannot be calculated so straightforwardly.  There is an additional element you need to consider.  The wattage needed will also depend on how many degrees you want to raise your water’s temperature.

This has to do with the temperature of the room the fish tank is in.  For example, if your room temperature is 65 degrees and your target water temperature is 74 degrees, you need to raise your water temperature by 9 degrees.  

Depending on the amount of degrees you need to increase, the watts are also determined. This does not change if your number is between a certain degree range.  So if you want to increase up to 9 degrees F, there is no wattage upgrade.

But if you want to change double that amount (18 degrees), you will add an additional 25 watts to your heater.  The same applies if you want to change even higher (27 degrees)- add another 25 watts. 

Look at the chart below for a general reference when making your selection.

You can see that if your tank size is very high and you need to increase your temperature by a lot, you may need to use two water heaters.  If you need to use two heaters, put them on opposite sides of the tank to ensure even heating.

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Other Considerations For Aquarium Heater Wattage Per Gallon

Always keep in mind that heat rises.  So you will need to think about the placement of the tube and the height of the tube.  Try to find a tube that is as high as your tank.  This will make sure you have the most successful heating.

Use a thermometer to keep track of the temperature.  Make sure your thermometer doesn’t have any cracks in it.  This will give you an inaccurate reading and could damage your system in the long run. 

If you really need a high water temperature, try to avoid putting the tank in very cold areas or areas with little sunlight. This means don’t put it by a dark cold window that isn’t fully sealed in the winter.  The air temperature directly affects your tank water temperature.  

If you want to raise tropical fish, you need to be aware of the water temperature needs before building your system.  Once you have the other elements of your design set up, follow our guidelines to select the right aquarium heater wattage per gallon.  

This is a very important detail for your tank system.  Be sure not to overlook it.  As usual, be careful when working with electronics and water.  Set up your cables and electricity safely so that it avoids coming into contact with the tank water.

When you need to clean and empty your tank, make sure to unplug your heater to avoid any risk of electrocution. Also, pay attention to your heater’s indicator light to make sure it is functioning properly.  If it is broken and you do not notice, diseases may quickly spread in your tank.  

As long as you pay careful attention, you should not have any major issues with your aquarium heater.

Please feel free to comment and ask questions below!

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