Heaters in a nano aquarium are more important than your average-sized fish tank. Since nano aquariums hold a smaller volume of water than standard-sized fish tanks, so they do not retain heat very well. Even if the room temperature falls, larger aquariums will retain the heat for an extended period. It may take hours for the water temperature to start dropping. However, in a small nano tank, the rise and fall in room temperature will more immediately affect the water temperature.
As ectothermic animals, fish rely on the environment to maintain their body temperature. They could die if the water temperature falls out of their desired range. Even if the water temperature is within a desirable range, a rapid fluctuation in the temperature could stress the fish.
Since nano aquariums are prone to temperature fluctuations, it is up to the fishkeeper to monitor and maintain the water temperature. Therefore, invest in a reliable aquarium heater for your nano aquarium. Don’t forget to get an aquarium thermometer as well.
For heaters for larger aquariums, refer to the Aquarium Heater Guide.
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What is Different about a Nano Tank Heater?
A heater for a nano aquarium needs to be the right size.
First, it must be the right size regarding heating capacity or wattage. The general rule of thumb is to get a heater with a capacity of 5 watts per gallon of water. If you have a small nano tank of 5-10 gallons, get a 50-watt heater. If you have a 15-20 gallon tank, get a 100-watt heater.
Second, consider the physical size and shape of the heater. If you have a nano tank, a standard heater may not fit. Find an aquarium heater that will fit. If possible, find a heater that is low profile. This will help maintain the aesthetics of your aquarium tank.
Do I need a Heater for my Nano tank?
Surprising as it may sound, not all nano tanks require a heater. Depending on where you live and what type of fish you wish to keep, you may or may not need an aquarium heater for your nano tank.
First, you may not need a heater if you live in a temperate climate. Also, you may not need a heater if you intend to keep fish that prefer colder water temperatures, such as goldfish and white cloud mountain minnows.
However, if you intend to keep tropical fish, you will likely need to invest in an aquarium heater. Much tropical fish prefer a water temperature of around 78 degrees Fahrenheit. Climates in most regions do not hold this temperature year-round.
Main types of Aquarium Heaters
There are three main types of nano aquarium heaters: submersible heaters, immersible heaters, and pad heaters.
Submersible heaters are the most popular option for nano aquarium tanks. They are often placed on the aquarium wall with suction cups. Since it is submersible, it can be installed vertically or horizontally.
Immersible heaters are not fully submersible. The heating mechanism will be placed under the water level, but a portion of the heater must stay above the water. This means you do not have to get your hands wet when adjusting the temperature level. However, you would have to make sure to turn the heater off during water changes because it will be exposed to dry air. If the heater is exposed to dry air and is left on, the heater may overheat and start to malfunction.
Pad heaters, or under gravel heaters, are common for small nano tanks under 5 gallons. They are designed to be installed on the very bottom of the aquarium. The temperature setting on these small pad heaters is often preset. This makes it very easy to install. Simply place it underneath the aquarium gravel, and plug it in. There is no need for calibration.
What size Aquarium Heater do I need?
When choosing the right size for your aquarium heater, the general rule of thumb is to get approximately 5 watts per gallon of water. While this is only a general guideline, it can be useful when trying to estimate the wattage requirements.
When sizing the heater size for your tank, various factors are considered.
- The volume of water (size of tank)
- Temperature of room
- Amount of heat retained in the aquarium
- Heat output variance depends on different heater manufacturer
Below is a chart that provides a starting point for choosing the correct heater size.
| Tank Size | To heat by 5° C | To heat by 10° C | To heat by 15 °C |
| 5 Gallon | 25 watts | 50 watts | 75 watts |
| 10 Gallon | 50 watts | 75 watts | 75 watts |
| 20 Gallon | 50 watts | 75 watts | 150 watts |
Best Nano Aquarium Heaters
There are a lot of different nano aquarium heaters on the market. Having many options is good, but choosing the right heater can make it difficult. Here are a few suggestions that we have for your nano aquarium based on the size.
Best Nano Aquarium heater for tanks of sizes 1 to 2.5 gallons
This may be the heater for you if you have a very small fish tank. This is one of the smallest heaters on the market with temperature control.
Out of the box, it is set for 78° F, which is the ideal temperature for most tropical fish. Once the temperature in the tank exceeds this, the heater automatically switches off and switches back on once the temperature drops below this mark.
It is a fully submersible design with discreet lines, making it unobtrusive in even the smallest of tanks.
Best Nano Aquarium heater for tanks of sizes 2 to 5 gallons
The smallest adjustable heater on the market is the Hydor Theo. It is adjustable from 19 – 33° C with a simple dial twist. It is a fully submersible heater and is available in 25W and 50W, both of which are only 7 inches in length.
In recent tests conducted by a fish lab, it was found to maintain temperatures within 1° F of its selected setting. A crucial benchmark for any nano tank heater.
Due to its small size and the fact that it is fully submersible, this little heater can be placed almost anywhere in your tank.
Best Nano Aquarium heater for tanks of size 6 to 10 gallons
The Cobal Neotherm is an awesome aquarium heater for nano tanks. However, it comes in various sizes and is one of the best aquarium heaters for fish tanks of all sizes.
Measured accuracy has shown that it stays within 0.5° F of its set temperature, which is remarkably accurate.
This is another fully submersible aquarium heater, so that the installation options can be very versatile.
Tips for Using Aquarium Heaters
Understanding the heating requirements for your fish tank and choosing the right aquarium heater is important. However, it is also important to understand how to use it. Here are a few tips on how to use your aquarium heater:
- Always unplug your heater when changing the water. If the heater is left on while exposed to air, it can overheat and break.
- Install the heater where there is adequate water flow. For example, placing it near the outflow of your aquarium filter. This will allow the heat to disperse throughout the aquarium properly. If the heater is placed in a stagnant area, the water temperature may fluctuate throughout the aquarium.
- Use a thermometer to keep an eye on the water temperature. Many heaters do have a temperature reading on the unit but do not rely on this alone.
